SharpCap User Manual

SharpCap User Manual
SharpCap 2.9 User Manual
SharpCap User Manual
Copyright ©2017 Robin Glover and David Richards
This version describes SharpCap 2.9.
SharpCap is an image capture application designed primarily
for astrophotography and video astronomy.
Support can be obtained via the SharpCap forum at http://forums.sharpcap.co.uk .
Page 1 of 157
SharpCap 2.9 User Manual
Table of Contents
1
Foreword ......................................................................................................................................... 9
2
Requirements .................................................................................................................................. 9
2.1
Supported Devices .................................................................................................................. 9
2.1.1
Altair Cameras ............................................................................................................... 10
2.1.2
Basler Cameras.............................................................................................................. 10
2.1.3
Celestron/Imaging Source Cameras .............................................................................. 10
2.1.4
iNova Cameras .............................................................................................................. 10
2.1.5
QHY Cameras ................................................................................................................ 10
2.1.6
ZWO Cameras................................................................................................................ 10
2.1.7
ASCOM Cameras ........................................................................................................... 10
2.1.8
DirectShow Cameras ..................................................................................................... 11
2.1.9
Choosing Between ASCOM and DirectShow................................................................. 11
2.2
Software ................................................................................................................................ 11
2.3
Hardware .............................................................................................................................. 12
2.3.1
Minimum Hardware Specification ................................................................................ 12
2.3.2
Recommended Hardware Specification ....................................................................... 12
3
Quick Start..................................................................................................................................... 13
4
Slow Start ...................................................................................................................................... 15
5
6
4.1
Installing the Camera Driver ................................................................................................. 15
4.2
Installing SharpCap................................................................................................................ 15
4.3
Testing SharpCap .................................................................................................................. 16
4.4
Removing SharpCap .............................................................................................................. 18
Introduction to the SharpCap User Interface ............................................................................... 19
5.1
Title Bar ................................................................................................................................. 20
5.2
Menu Bar............................................................................................................................... 20
5.3
Tool Bar ................................................................................................................................. 20
5.4
Capture Display Area............................................................................................................. 21
5.5
Camera Control Panel ........................................................................................................... 21
5.6
Work Area ............................................................................................................................. 22
5.7
Status Bar .............................................................................................................................. 22
The Menu Bar................................................................................................................................ 24
6.1
File ......................................................................................................................................... 24
Page 2 of 157
SharpCap 2.9 User Manual
6.1.1
SharpCap Settings ......................................................................................................... 24
6.1.2
Exit................................................................................................................................. 24
6.2
6.2.1
Rescan for Cameras....................................................................................................... 25
6.2.2
Available Cameras ......................................................................................................... 25
6.3
7
Cameras ................................................................................................................................ 24
Options .................................................................................................................................. 25
6.3.1
Full Screen ..................................................................................................................... 25
6.3.2
Reset Control Order ...................................................................................................... 25
6.3.3
Other Options ............................................................................................................... 26
6.4
Capture.................................................................................................................................. 26
6.5
Tools ...................................................................................................................................... 27
6.5.1
Live Stack....................................................................................................................... 27
6.5.2
Polar Align ..................................................................................................................... 27
6.6
Scripting ................................................................................................................................ 27
6.7
Help ....................................................................................................................................... 27
6.7.1
View Help ...................................................................................................................... 27
6.7.2
Check for Updates ......................................................................................................... 27
6.7.3
Report a Bug.................................................................................................................. 28
6.7.4
Show Log ....................................................................................................................... 28
6.7.5
About............................................................................................................................. 30
The Tool Bar .................................................................................................................................. 31
7.1
Start Capture ......................................................................................................................... 31
7.2
Quick Capture ....................................................................................................................... 31
7.3
Stop Capture ......................................................................................................................... 31
7.4
Pause ..................................................................................................................................... 31
7.5
Snapshot ............................................................................................................................... 31
7.6
Live Stack............................................................................................................................... 32
7.7
Object Name ......................................................................................................................... 32
7.8
Preview FX (effects) .............................................................................................................. 32
7.8.1
None .............................................................................................................................. 33
7.8.2
Highlight Over Exposed ................................................................................................. 33
7.8.3
Image Boost .................................................................................................................. 33
7.8.4
Image Boost More......................................................................................................... 34
7.8.5
Frame Stack (3) ............................................................................................................. 34
7.8.6
Frame Stack (5) ............................................................................................................. 34
7.8.7
Frame Stack (10) ........................................................................................................... 35
Page 3 of 157
SharpCap 2.9 User Manual
7.8.8
RGB Align....................................................................................................................... 35
7.8.9
Stop Motion Video ........................................................................................................ 36
7.9
FX Selection Area .................................................................................................................. 36
7.10
Reticule Overlays................................................................................................................... 36
7.10.1
No Reticule .................................................................................................................... 36
7.10.2
Crosshairs ...................................................................................................................... 36
7.10.3
Circle.............................................................................................................................. 37
7.11
Zoom ..................................................................................................................................... 37
7.12
Image Histogram ................................................................................................................... 37
7.13
Calculate Focus Score............................................................................................................ 38
8
Camera Control Panel ................................................................................................................... 39
8.1
Capture Profiles..................................................................................................................... 40
8.2
Capture Format and Area ..................................................................................................... 41
8.3
Camera Controls ................................................................................................................... 41
8.4
Image Controls ...................................................................................................................... 42
8.5
Pre-processing....................................................................................................................... 42
8.6
Display Controls .................................................................................................................... 43
8.7
Testing Controls .................................................................................................................... 43
8.8
Other Controls....................................................................................................................... 43
9
Capturing Videos and Images ....................................................................................................... 44
9.1
Start Capture ......................................................................................................................... 44
9.2
Stop Capture ......................................................................................................................... 46
9.3
Delete Last Capture............................................................................................................... 46
9.4
Open Capture Folder............................................................................................................. 47
9.5
Capture Dark ......................................................................................................................... 47
10
Camera Basics ........................................................................................................................... 48
10.1
Colour Spaces Explained ....................................................................................................... 48
10.2
Uncompressed Colour Spaces............................................................................................... 48
10.2.1
RGB24............................................................................................................................ 48
10.2.2
RGB32............................................................................................................................ 48
10.2.3
MONO8 (also Y800)....................................................................................................... 49
10.2.4
MONO16 ....................................................................................................................... 49
10.2.5
RAW8 ............................................................................................................................ 50
10.2.6
RAW16 .......................................................................................................................... 51
10.3
Compressed Colour Spaces ................................................................................................... 51
10.3.1
YUY2 / YUV .................................................................................................................... 51
Page 4 of 157
SharpCap 2.9 User Manual
10.3.2
I420 ............................................................................................................................... 51
10.3.3
MJPEG ........................................................................................................................... 51
10.4
Choosing the Correct Colour Space ...................................................................................... 52
10.5
Capture Formats Explained ................................................................................................... 52
10.5.1
AVI ................................................................................................................................. 52
10.5.2
SER................................................................................................................................. 52
10.5.3
PNG ............................................................................................................................... 53
10.5.4
FITS ................................................................................................................................ 54
11
Camera Controls ....................................................................................................................... 55
11.1
Common Camera Controls .................................................................................................... 55
11.1.1
Capture Format and Area ............................................................................................. 55
11.1.1.1
Binning .................................................................................................................. 56
11.1.1.2
Additive Binning .................................................................................................... 57
11.1.1.3
Averaging Binning ................................................................................................. 57
11.1.2
Camera Controls ........................................................................................................... 58
11.1.3
Image Controls .............................................................................................................. 59
11.1.4
Pre-processing............................................................................................................... 60
11.1.5
Display Controls ............................................................................................................ 60
11.2
Camera Specific Controls ...................................................................................................... 61
11.2.1
Altair Camera Controls .................................................................................................. 61
11.2.2
ASCOM Camera Controls .............................................................................................. 62
11.2.3
Basler Camera Controls ................................................................................................. 62
11.2.4
Celestron/Imaging Source Camera Controls ................................................................. 64
11.2.5
iNova Camera Controls ................................................................................................. 64
11.2.6
QHY Camera Controls ................................................................................................... 65
11.2.7
ZWO Camera Controls................................................................................................... 67
11.2.8
DirectShow Cameras ..................................................................................................... 69
11.2.8.1
Webcams............................................................................................................... 69
11.2.8.2
Microsoft LifeCam (webcam) ................................................................................ 69
11.2.9
Frame Grabbers ............................................................................................................ 71
11.2.10 Modified Webcams ....................................................................................................... 73
11.2.11 DirectShow Controls ..................................................................................................... 74
11.2.12 Test Cameras ................................................................................................................. 74
12
The Histogram ........................................................................................................................... 76
12.1
The Histogram in Detail ........................................................................................................ 77
12.2
Understanding the Histogram Axes ...................................................................................... 79
Page 5 of 157
SharpCap 2.9 User Manual
12.3
Linear and Logarithmic Scales ............................................................................................... 80
12.4
Using the Histogram to Improve Image Quality ................................................................... 82
12.5
Worked Examples ................................................................................................................. 84
12.5.1
A Monochrome Deep Sky Example ............................................................................... 84
12.5.2
A Colour Deep Sky Example .......................................................................................... 87
13
Live Stacking .............................................................................................................................. 88
13.1
The Live Stacking User Interface ........................................................................................... 88
13.1.1
Left Panel ...................................................................................................................... 89
13.1.2
Status Tab...................................................................................................................... 90
13.1.3
Histogram Tab ............................................................................................................... 91
13.1.4
Alignment Tab ............................................................................................................... 92
13.1.5
Filter Tab ....................................................................................................................... 94
13.1.6
Darks Tab....................................................................................................................... 94
13.1.7
Log Tab .......................................................................................................................... 95
13.2
Live Stack Reference ............................................................................................................. 95
13.3
Using Live Stacking ................................................................................................................ 95
13.4
Sample Live Stack Session ..................................................................................................... 96
13.4.1
Trouble Shooting Live Stack ........................................................................................ 100
13.4.2
Stretching the Live Stack Image .................................................................................. 101
14
Focusing .................................................................................................................................. 103
14.1
Introduction ........................................................................................................................ 103
14.2
The Focusing Tools .............................................................................................................. 104
14.3
Which Focus Tool Should Be Used? .................................................................................... 104
14.4
Focusing Procedure............................................................................................................. 105
14.5
Overview of Display ............................................................................................................ 107
14.5.1
Focus Tools Controls ................................................................................................... 109
14.5.2
The Graph Pane........................................................................................................... 111
14.5.2.1
History Tab .......................................................................................................... 111
14.5.2.2
Graph Tab ............................................................................................................ 112
14.5.2.3
History and Graph Manipulation ........................................................................ 114
14.6
Setting the Correct Black Level ........................................................................................... 115
14.7
Using a Bahtinov Mask ........................................................................................................ 116
15
Polar Alignment....................................................................................................................... 118
15.1
How does it Work? .............................................................................................................. 118
15.2
What is required?................................................................................................................ 118
15.3
Step-By-Step........................................................................................................................ 118
Page 6 of 157
SharpCap 2.9 User Manual
15.4
16
Tips ...................................................................................................................................... 121
Configuring SharpCap ............................................................................................................. 123
16.1
General Tab ......................................................................................................................... 123
16.1.1
Automatically connect to camera when SharpCap starts ........................................... 123
16.1.2
Display in night vision colours ..................................................................................... 123
16.1.3
Default Zoom .............................................................................................................. 124
16.1.4
Saved target names..................................................................................................... 124
16.1.5
Show tips when SharpCap starts................................................................................. 125
16.1.6
Start cameras with ‘Auto’ output format (for supported cameras) ........................... 125
16.1.7
Preferred Video Format .............................................................................................. 125
16.1.8
Preferred Still Format.................................................................................................. 125
16.2
Hardware Tab...................................................................................................................... 126
16.3
Filenames Tab ..................................................................................................................... 127
16.3.1
Save captured files to .................................................................................................. 127
16.3.2
Test Write Speed ......................................................................................................... 127
16.3.3
Organise captured files into subfolders ...................................................................... 127
16.3.4
Date and then Target Name........................................................................................ 127
16.3.5
Target Name and then Date........................................................................................ 128
16.3.6
Create WinJUPOS Compatible File Names .................................................................. 128
16.3.7
Use UTC times in files and folder names .................................................................... 128
16.3.8
Use sortable date format (YYYY-MM-DD) ................................................................... 129
16.3.9
Save capture settings file alongside each capture ...................................................... 129
16.4
17
Start-up Scripts Tab ............................................................................................................. 129
Capturing and Using Dark Frames........................................................................................... 131
17.1
Camera Noise ...................................................................................................................... 131
17.2
Dark Frames Explained........................................................................................................ 132
17.3
Capture Dark Dialogue ........................................................................................................ 133
18
Scripting .................................................................................................................................. 135
18.1
The Scripting Console.......................................................................................................... 135
18.2
Run a Script ......................................................................................................................... 137
18.3
Scripting Tutorial ................................................................................................................. 138
18.3.1
Create a Script ............................................................................................................. 138
18.3.2
SharpCap Scripting Object Model Reference .............................................................. 142
18.3.3
The Camera Object...................................................................................................... 142
18.3.4
The Control Object ...................................................................................................... 144
18.4
Scripting Samples ................................................................................................................ 144
Page 7 of 157
SharpCap 2.9 User Manual
18.4.1
Periodic Capture and Timestamp Image ..................................................................... 145
18.4.2
Controlling the Selection Rectangle ............................................................................ 145
18.4.3
Example Task to Script ................................................................................................ 146
19
ASCOM Hardware Control ...................................................................................................... 147
19.1
Focuser Control ................................................................................................................... 147
19.2
Filter Wheel Control ............................................................................................................ 147
19.3
Mount Control .................................................................................................................... 147
20
Bugs & Crashes........................................................................................................................ 149
20.1
How to Report a Bug ........................................................................................................... 149
20.2
How to Report a Crash ........................................................................................................ 149
20.2.1
Submitting a Crash Report .......................................................................................... 149
20.2.2
No Crash Report? ........................................................................................................ 150
21
Trouble Shooting ..................................................................................................................... 151
21.1
Hardware ............................................................................................................................ 151
21.2
Software .............................................................................................................................. 152
21.3
Imaging................................................................................................................................ 152
21.3.1
Image Too Bright ......................................................................................................... 152
21.3.2
Jumpy AVI Will Not Stack ............................................................................................ 152
21.3.3
Grainy Image ............................................................................................................... 152
21.3.4
Histogram with Gaps ................................................................................................... 153
21.3.5
Colours are Wrong ...................................................................................................... 153
22
Appendix ................................................................................................................................. 155
22.1
Test Write Speed ................................................................................................................. 155
22.2
SharpCap Uninstall Clean-up............................................................................................... 156
22.3
Maintenance of Capture Profiles ........................................................................................ 156
23
Useful Software....................................................................................................................... 157
24
Glossary ................................................................................................................................... 157
Page 8 of 157
SharpCap 2.9 User Manual
1 Foreword
SharpCap was born in frustration in February 2010. The frustration was with the typical applications
used for webcam capture in Astrophotography at the time. AMCAP was a prime example – it made it
very hard to adjust the settings on your camera and very easy to do silly things like write over the
previous capture file. These shortcomings were brought even more obvious when you were trying to
use the program in the dark, on a laptop and while wearing gloves.
My response to this – a standard one for a software developer who has just encountered a poorly
designed application – was to think to myself ‘I can do better than that’. Perhaps more unusually I
actually decided that I would do better than that and I started to write SharpCap over the next few
days. One of the hard parts of a software project is often deciding on a name, but the name
SharpCap was easy to arrive at – it comes from the programming language it is written in – C#
(pronounced C-sharp).
Through its first year, SharpCap remained a fairly simple webcam capture application that was
designed to be easy to use, to use standard, familiar Windows UI elements and to show the controls
for the camera to the user at all times. This seemed to be enough of an improvement over the
available alternatives to persuade a large number of people to start using SharpCap.
About a year after SharpCap’s first release something unexpected (to me) happened – I was
approached out of the blue by an astronomy retailer selling Basler cameras asking if it would be
possible to make SharpCap work with those cameras and offering to provide a sample camera to
work with. This chance event changed SharpCap’s direction from a webcam only application to one
that today supports a wide range of dedicated astro-imaging hardware.
Over the years as well as adding support for more cameras, SharpCap has also added many more
features to the extent that this user manual is now necessary as the application is sadly no longer
simple enough to ‘just use’. The primary aim throughout has been to try to make things that are
difficult simpler – finding objects can be hard so the various image boost effects help find faint or
out-of-focus targets; focusing can be hard so there are six focus assistance tools; DSO imaging is hard
so live stacking makes it easier and of course polar alignment can be hard, but it is made simpler
with SharpCap’s easy to use polar alignment tool.
I hope that you enjoy using SharpCap and that it indeed makes your astro-imaging easier.
Clear Skies!
Robin Glover, April 2017
2 Requirements
2.1 Supported Devices
SharpCap supports a wide range of cameras. These can be divided into 3 basic categories:
1. Cameras supported directly by SharpCap – these include many brands of dedicated
astronomy cameras including models by Altair, Basler, Celestron, Imaging Source, iNova,
QHY and ZWO.
2. Cameras supported via a Windows Webcam driver – includes most webcams (modified and
unmodified), USB frame grabbers and is also an option for many specialised cameras where
the manufacturer provides a webcam driver (sometimes called a WDM or DirectShow
driver).
Page 9 of 157
SharpCap 2.9 User Manual
3. Cameras supported via an ASCOM driver – many astronomy camera manufacturers provide
ASCOM drivers for their products and SharpCap can use these to communicate with the
camera.
Sometimes a camera can be accessed by two (or even all three) of the options above. If that
happens, it is usually best to prefer to use the direct support for the camera as this will give the most
control over the camera’s functionality.
2.1.1 Altair Cameras
A UK based supplier of a wide range of CMOS cameras for guiding, solar, planetary, lunar and deep
sky imaging. Altair cameras can also be purchased from a range of dealers in the UK and other
countries. Altair’s website can be found at https://www.altairastro.com/ .
2.1.2 Basler Cameras
A German manufacturer of a wide range of industrial cameras, some of which are suitable for astro
imaging. SharpCap supports Basler cameras, including those with Gigabit Ethernet connectivity. On
some models of Basler cameras, SharpCap is capable of supporting exposures longer than the
camera's normal maximum limit by clever software control of the camera's manual exposure
triggers. Basler’s website can be found at http://www.baslerweb.com/en .
2.1.3 Celestron/Imaging Source Cameras
The Imaging Source provide a wide range of industrial cameras which have been used for astro
imaging for some time. Imaging Source manufactured cameras are now sold under the Celestron
brand. SharpCap should be able to control the full range of The Imaging Source and Celestron
cameras, although testing has covered the more common USB cameras only. The Imaging Source’s
website can be found at https://www.theimagingsource.com/ .
2.1.4 iNova Cameras
iNova sell a range of small sensor CMOS/CCD cameras aimed primarily at the astro imaging market,
primarily suitable for solar/lunar/planetary imaging and auto-guiding. iNova’s website can be found
at http://inovaccdusa.com/ .
2.1.5 QHY Cameras
QHY sell a wide range of CCD and CMOS cameras with sensor sizes ranging from webcam size to full
frame SLR and beyond. These cameras are primarily designed for the astro imaging and Scientific
markets. SharpCap supports the full range of QHY cameras and includes support for advanced
features such as built-in filter wheels, GPS timing modules and Peltier cooler control. QHY’s website
can be found at http://www.qhyccd.com/ .
2.1.6 ZWO Cameras
ZWO sell a range of CMOS cameras with low noise, high sensitivity sensors, ranging from webcam
size to full frame SLR. Their cameras are primarily designed for the astro imaging market, including
useful features such as built in USB hubs on some models. SharpCap supports the full range of ZWO
cameras including control of advanced features such as Peltier cooler control and USB bandwidth
adjustment. ZWO’s website can be found at https://astronomy-imaging-camera.com/ .
2.1.7 ASCOM Cameras
Many astro cameras have ASCOM drivers and SharpCap can use these drivers to control such
cameras. This can be a good fall back option when SharpCap does not have direct support for a
camera. The ASCOM Standards website can be found at
http://www.ascom-standards.org/Downloads/CameraDrivers.htm .
Page 10 of 157
SharpCap 2.9 User Manual
2.1.8 DirectShow Cameras
Microsoft DirectShow is an architecture for streaming media on the Microsoft Windows platform.
There are a vast number of webcams and frame grabbers on the market. The controls available in
SharpCap are determined by the driver – SharpCap just shows the controls the driver makes
available.
2.1.9 Choosing Between ASCOM and DirectShow
If a camera appears as ASCOM and DirectShow – which should be chosen?
If a camera not directly supported by SharpCap is to be used, there are two options when connecting
to it – ASCOM drivers or DirectShow drivers. Each have their pros and cons.
ASCOM
DirectShow
Pros:
• Direct control of exposure (continuously
variable) in the SharpCap panel.
• Binning may be available.
• ROI may be available (2.10 and up).
• Bit depths of >8 and RAW modes may be
available.
• Long exposures likely to be available.
Pros:
• A better selection of camera controls
available in the panel (gamma, brightness,
contrast, etc.).
• Long exposures may be available (i.e. 1s, 2s,
4s, 8s, 16s, etc.).
• Region of Interest (ROI) may be available.
• Extra controls may be available in the
camera's DirectShow config dialog.
• High frame rates possible.
• Less likely to have compatibility issues than
ASCOM.
Cons:
• Few other controls in the SharpCap panel
as ASCOM doesn't allow for many except
exposure and gain.
• ASCOM is relatively slow, so frame rates
will be slower.
• ASCOM can be unreliable because each
manufacturer interprets the standard in
their own way, which can lead to some
ASCOM drivers being incompatible with
SharpCap.
Cons:
• Exposure only changeable in multiples of 2.
• Bit depths limited to 8 bits and RAW modes
unlikely to be available.
• Can only save videos to AVI and images to
PNG (2.9 only, this restriction removed in
2.10).
• Using an astro camera via DirectShow isn't
as good as using it directly (less controls,
less control over exposure), but it is better
than nothing.
2.2 Software
SharpCap runs on Microsoft Windows. The minimum version requirement is:
•
•
SharpCap 2.9 (or older versions) – Windows XP, Vista, 7, 8, 8.1, 10
SharpCap 2.10 (or newer versions) – Windows Vista, 7, 8, 8.1, 10
SharpCap is a 32-bit application and will install and run on both the 32-bit and 64-bit versions of
Windows.
Multiple major versions can co-exist, for example 2.8, 2.9 and 2.10 can be installed together on the
same machine. Only one minor version can be installed, for example only one of 2.9.3055 and
2.9.3011 can be installed at any one time.
Page 11 of 157
SharpCap 2.9 User Manual
Windows XP, although now out of Microsoft support, will work with older cameras. The problem
with this version of the operating system is manufacturer driver support for XP will dwindle,
therefore newer cameras will be unable to run on the platform.
Windows 7, 8.1 and 10 are well supported by manufacturers. Windows 7 will go end of life in 2020
and at this point, Microsoft support will cease.
2.3 Hardware
The minimum hardware requirement is dependent on the type of camera being used. When
purchasing a camera, look closely at the manufacturer/vendor recommended minimum PC
specification.
The following areas need to be considered to achieve the best frame rates:
•
•
•
•
•
Processor, i5 or i7 is better.
Memory, 3Gb maximum for 32-bit Windows, 64-bit needs at least 4Gb.
Disk, SSD is faster than conventional drive.
USB, USB3 (5Gb/s) is 10x faster than USB2 (480Mb/s).
Windows 32/64-bit, 64-bit supports > 3Gb memory.
SharpCap is designed to take advantage of the multiple CPU cores available on most modern
computers and will perform better for fast cameras if more than one CPU core is available.
Consider the hardware demands when purchasing high frame rate cameras.
2.3.1 Minimum Hardware Specification
A 640x480 resolution webcam will work well on a low specification PC. A ThinkPad X61 (used to
produce the examples in this manual) satisfies this requirement. The following specification can
achieve 30fps at 640 x 480 with a USB2 webcam.
•
•
•
•
Core 2Duo 1.86Ghz processor
4Gb (3Gb usable with 32-bit Windows)
120Gb SATA2 drive
Windows 10 32-bit
2.3.2 Recommended Hardware Specification
A dedicated astronomy camera capable of 3000x2000 pixels at 50fps will require a fast processor,
more memory, an SSD and a USB3 port to achieve maximum performance.
If intending to use high resolution cameras (10 Megapixels or more), ensure the capture PC/laptop
has:
•
•
•
•
A minimum of i5 processor.
A large capacity hard drive (500Gb or more) with SSD preferred.
At least 4Gb (preferably 8Gb or more) of memory.
A 64-bit version of the Windows operating system.
This configuration allows SharpCap to access more memory, thus reducing the likelihood of memory
exhaustion while capturing. This applies when working in RGB mode or at bit depths of 12 or 16 bits
per pixel.
Page 12 of 157
SharpCap 2.9 User Manual
3 Quick Start
This section describes getting started quickly and is intended for the experienced or impatient user.
1. Download the latest camera driver from the manufacturer’s website.
2. Install the camera driver – there may be a need to approve an administrator prompt or run
the installer as administrator.
3. Restart the PC/laptop.
4. Attach the camera.
5. Download the latest SharpCap from http://www.sharpcap.co.uk/sharpcap/downloads .
6. Install SharpCap – there may be a need to approve an administrator prompt or run the
installer as administrator.
7. Go to the camera menu and select the camera from the list of devices.
8. If the camera is attached to a telescope or lens, a picture from the camera should be seen in
the display area.
Page 13 of 157
SharpCap 2.9 User Manual
9. Use the Camera Control Panel at the right-hand side of the screen to control settings such as
exposure and gain. The image should change in response to the controls being adjusted.
10. Use the Start Capture (or Quick Capture) buttons to start a video capture to a new file or the
Snapshot button to capture a single frame to a file.
Once the capture has completed, a Notification Bar will appear directly below the Tool Bar.
Click the highlighted link to go directly to the folder holding the captured image.
11. The installation and testing of SharpCap is now complete.
Page 14 of 157
SharpCap 2.9 User Manual
4 Slow Start
This section is a step by step getting started guide.
4.1 Installing the Camera Driver
Do not connect a camera until its drivers have been installed. Drivers are best installed from a
Windows user account which has administrative privileges. The drivers can be obtained in three
ways, depending on the camera:
1. Drivers delivered on a CDROM provided with the camera. These might not be the latest
version, so consider option 2.
2. Links to camera manufacturers’ websites can be found at http://www.sharpcap.co.uk/ , in
the Supported Devices section or in Camera Controls in this document under the
appropriate manufacturer.
3. Microsoft supported webcams (which work with DirectShow) may download a driver
automatically once the camera is plugged in. This certainly works, for example, with the
Microsoft LifeCam under Windows 10. However, earlier versions of Windows require the
LifeCam drivers to be downloaded from Microsoft.
Once the camera drivers are installed, restart Windows, plug in the camera and check via Control
Panel > Devices to see if the device (camera) is working properly.
4.2 Installing SharpCap
The download and installation of SharpCap is described here.
1. Download SharpCap from http://www.sharpcap.co.uk/downloads . The single download is
suitable for both 32-bit and 64-bit versions of Windows.
2. Navigate to the folder where SharpCap has been loaded. Double click on the file
SharpcapInstall-version-number.exe to install.
3. Supply an administrator account name and password if requested and click Install.
4. When the Installation Successfully Completed message appears, click Close.
Page 15 of 157
SharpCap 2.9 User Manual
5. SharpCap is now installed.
4.3 Testing SharpCap
Consider carrying out the initial testing from inside with the telescope and camera pointing at an
object such as a tree, chimney, lamp or mast. Choose a large object.
12. Connect the camera to the telescope.
13. Connect the camera to the PC.
14. Start SharpCap. From the main menu, select Cameras. Ensure the camera is selected
(ticked) – in this example, the camera is a Microsoft LifeCam. If the camera name appears
twice, select the highest one on the list.
15. This is SharpCap’s Main Screen.
Page 16 of 157
SharpCap 2.9 User Manual
Key areas are:
Capture Display Area – the image the camera sees is displayed here.
Quick Capture Button – will start a video capture to a new file.
Snapshot Button – will capture a single frame to a PNG file.
Exposure – controls the camera exposure.
If focusing of the telescope cannot be reached, try removing diagonals or adding extensions.
16. Try the Snapshot button. A Notification Bar will appear directly below the Tool Bar. Click
the highlighted link to go directly to the folder holding the captured image.
17. This folder (SharpCap Captures\YYY-MM-DD) which is on the desktop, will contain 2 files.
One is the image, the other is a text file containing the camera settings.
Page 17 of 157
SharpCap 2.9 User Manual
18. The camera settings file looks like this:
19. Try the Quick Capture button. At the bottom-right of the main screen, a progress bar should
appear.
20. When this video capture has completed, click the link in the Notification Bar. The capture
folder should contain a video file and a camera settings file. Double click the video to play it.
21. If all the above has worked, the SharpCap and camera installation has been successfully
tested.
4.4 Removing SharpCap
This section describes the complete removal of SharpCap and all its ancillary settings. This action
might be required to perform a clean install with all old settings removed. This work is best carried
out with an account with administrator privileges
Uninstall SharpCap – either from Control Panel or via the Start button, go to Programs and Features,
highlight SharpCap and Uninstall. [Note: there may be multiple versions to choose from.]
See the Appendix for additional (non-essential) clean-up actions.
Page 18 of 157
SharpCap 2.9 User Manual
5 Introduction to the SharpCap User Interface
Upon starting SharpCap and dismissing the Tip of the Day message, the following screen appears:
The SharpCap main screen consists of seven permanent areas and one temporary area.
The permanent areas are:
1. Title Bar – shows the selected (active) camera (if any) and the default capture folder.
2. Menu Bar – gives access to SharpCap functions.
3. Tool Bar – gives quick access to tools frequently used for image capture. When an image
capture has completed a Notification Bar, giving save details, will appear below the Tool Bar.
4. Capture Display Area – shows the image currently being captured by the selected camera.
5. Camera Control Panel – gives access to all available controls for the selected camera. Items
displayed in this panel will vary depending on the type, model and level of support of the
connected camera.
6. Work Area – used as a display area by tools such as Image Histogram, Calculate Focus Score
and Live Stack.
7. Status Bar – gives ongoing information about frames captured/dropped and frame rate.
During a capture, a progress bar will appear at the right-hand end of the status bar.
Page 19 of 157
SharpCap 2.9 User Manual
The temporary area is:
1. Notification Bar – appears below the Tool Bar upon completion of a Capture or Snapshot
and provides a clickable link to go directly to the appropriate folder where the file has been
stored. The notification bar is also used to provide other information – a green notification
bar indicates success; a yellow bar indicates a warning and an orange bar indicates an error
has occurred.
5.1 Title Bar
The Title Bar shows the selected (active) camera and the default folder for saving image captures.
If no camera is active, only the default folder for saving image captures is shown.
5.2 Menu Bar
The Menu Bar gives structured access to many aspects of SharpCap functionality.
5.3 Tool Bar
The Tool Bar gives easy access to a collection of facilities commonly used when performing an image
capture.
From left to right, these are:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Start Capture
Quick Capture
Stop Capture
Pause
Snapshot
Live Stack
Object Name
Preview Effects (FX)
FX Selection Area
Reticule Overlays
Zoom
Image Histogram
Page 20 of 157
SharpCap 2.9 User Manual
13. Calculate Focus Score
If the SharpCap window is not wide enough to accommodate all the tool icons, the Tool Bar will look
like this with a down arrow at the right-hand end:
Click the down arrow to access the rest of the tool icons:
5.4 Capture Display Area
The Capture Display Area shows the view currently being seen by the active camera.
When a camera is selected in SharpCap (or SharpCap automatically selects a camera when it is
started), SharpCap starts grabbing and displaying frames straight away. SharpCap isn't saving these
frames, just showing them on the screen. Depending on the exposure length being used, the image
may update many times per second or only once every few seconds (or even less frequently).
SharpCap will only save images after use of the Start Capture or Snapshot buttons.
5.5 Camera Control Panel
The capabilities and available controls of the active camera are displayed in the Camera Control
Panel. These controls are used to adjust camera settings such as exposure, resolution, colour
balance and others. The groups and controls displayed can vary depending on:
•
•
The manufacturer of the attached camera.
The model of camera (even from the same manufacturer)
See Camera Controls for a full description. The controls are grouped logically and each group can be
expanded/closed as required.
Page 21 of 157
SharpCap 2.9 User Manual
5.6 Work Area
The Work Area is the display area for the following tools:
•
•
•
•
Live Stack
Histogram
Polar Align
Focus Score
For each tool, the title bar of the panel can be used to drag the panel out of the main SharpCap
form, for example to place it on a second monitor.
5.7 Status Bar
The Status bar at the bottom of the screen gives a constantly updated report on:
•
•
•
•
Frames captured
Frames dropped
Duration of capture
Capture speed, frames per second (fps)
Page 22 of 157
SharpCap 2.9 User Manual
When an image capture has been initiated, a progress bar is displayed at the right showing:
•
•
•
Frames completed
Frames remaining
Estimated finishing time
Page 23 of 157
SharpCap 2.9 User Manual
6 The Menu Bar
6.1 File
The File menu item has the following options.
6.1.1 SharpCap Settings
The SharpCap Settings defaults have been chosen to enable ease of use of the application with
minimal configuration required after installation, however adjustment to the settings can be made
here when necessary.
See Configuring SharpCap for a detailed description of the four tabs General, Hardware, Filenames,
and Startup Scripts.
6.1.2 Exit
Selecting Exit or Alt+F4 will perform an orderly shutdown of SharpCap.
6.2 Cameras
The Cameras menu item allows selection and de-selection of attached imaging devices. These may
be cameras or video capture devices (frame grabbers).
Two ‘built-in’ cameras are provided:
1. Test Camera 1 (Deep Sky), a simulation of a capture of the M42 Nebula in the Constellation
of Orion.
2. Test Camera 2 (High Speed), a simulation of a capture of Jupiter (the dark spot to the lower
left being the shadow of a moon).
These two test cameras can be used to learn the functionality of SharpCap without requiring a
telescope and camera.
[Note: some cameras (particularly ASCOM and DirectShow cameras) may show in the device list
even when they are not connected to the computer – selecting one of these cameras not currently
available will give an error message.]
Page 24 of 157
SharpCap 2.9 User Manual
6.2.1 Rescan for Cameras
If a camera connection is lost or a camera plugged in while SharpCap is open, use the Rescan option
to find the device.
SharpCap automatically rescans after a USB device is added to or removed from the computer. The
rescan button is mainly useful to detect network connected cameras (i.e. Basler or Point Grey Gig-E
cameras) as SharpCap cannot detect these being added to the network.
6.2.2 Available Cameras
Select the camera to use from the dropdown list.
There may be occasion when a camera appears twice in the available cameras list. If in doubt which
one to select, use the one highest in the list (because SharpCap tries to put the cameras it has the
best control over at the top of the list). See the Philips SPC 900NC in the graphic below.
Sometimes it is useful to close the camera currently in use without opening a different camera. This
can be achieved by returning to the Cameras menu and choosing the selected camera from the
menu again.
6.3 Options
The Options menu item has the following items.
6.3.1 Full Screen
The Full Screen option forces SharpCap to switch to full screen mode. This leaves only the Capture
Display Area and Camera Control Panel visible – there are no menu or tool bars available. To reverse
this situation, move the mouse pointer to the top of the screen and the menu will appear. The Full
Screen option can be unchecked.
6.3.2 Reset Control Order
In the Camera Control Panel, each control group has a handle at the top right corner. This handle
can be grabbed with a mouse and the control moved elsewhere in the Camera Control Panel to suit
Page 25 of 157
SharpCap 2.9 User Manual
individual preferences. By choosing Reset Control Order, the control groups can be returned to their
default order.
6.3.3 Other Options
Depending on the manufacturer/model of camera connected and selected in SharpCap, other menu
items may appear in the Options menu.
These are the additional menu items available when a Microsoft LifeCam (webcam) is connected and
selected.
6.4 Capture
The Capture menu item has the following options.
Capture allows control of:
•
•
The capture process.
The production of dark frames.
See Capturing Videos and Images for a detailed description of these menu items.
Page 26 of 157
SharpCap 2.9 User Manual
6.5 Tools
The Tools menu item provides access to specific functions which can assist in capturing images or
ensuring alignment of the telescope.
6.5.1 Live Stack
This option provides the same functionality as the Live Stack button located on the Tool Bar. See
Live Stacking for a full description of the tool.
<ALT> < L> can be used as a hot key combination to initiate Live Stack.
6.5.2 Polar Align
Selecting Polar Align will produce a set of screens to manage the alignment process. See Polar
Alignment for a detailed description.
6.6 Scripting
The Scripting menu item allows access to the Scripting Console and gives the ability to run existing
scripts and write new scripts. The scripts are based on Python. The functionality of SharpCap can be
extended by using scripting as a built-in programming language.
Scripting is an advanced topic and knowledge of it is not essential to be able to use SharpCap
effectively.
See Scripting for a full description.
6.7 Help
The Help menu item has the following options.
6.7.1 View Help
View Help will display a manual, in Windows help file format, installed as part of the of the SharpCap
software.
6.7.2 Check for Updates
Selecting Check for Updates will initiate a version check against the SharpCap website of the installed
versus latest version. If no updates are available, the message below is displayed.
Page 27 of 157
SharpCap 2.9 User Manual
If an update is available, a download and installation is offered.
6.7.3 Report a Bug
This option provides a simple mechanism to report possible bugs or issues directly to the developer.
The capture PC/laptop must have internet connectivity for this to work.
Fill in the text and press the Send button. It would be useful to provide contact details such as an
email address.
6.7.4 Show Log
SharpCap, in the background, is constantly logging events relating to the program.
Page 28 of 157
SharpCap 2.9 User Manual
Click the Copy to Clipboard button to copy the contents of the log. By opening Notepad (or other
text editor) the contents of the log can be pasted and a file saved. The information on how to send
the log file can be found at http://forums.sharpcap.co.uk/ .
Page 29 of 157
SharpCap 2.9 User Manual
6.7.5 About
The About window provides:
•
•
•
•
•
•
A link to the SharpCap website.
A message informing an upgrade to a SharpCap Pro License is available.
Acknowledgements.
A link to License Information.
A link to the SharpCap Facebook page.
Version and Change history. The currently installed version shown here is 2.9.3055.
Page 30 of 157
SharpCap 2.9 User Manual
7 The Tool Bar
7.1 Start Capture
The Start Capture button will start a video capture to a new file. The functionality is identical to
choosing Capture > Start Capture from the menu. See Capturing Videos and Images for a full
description.
7.2 Quick Capture
Clicking the Quick
Capture button will
initiate a video capture
to a new file but use a
pre-selected number of
frames or seconds.
To modify the preselected value, click the
down arrow and select
a new value. This value
will be ‘remembered’
for future quick
captures.
<ALT> < Q> can be used as a hot key combination to initiate a Quick Capture.
7.3 Stop Capture
When a capture is in-progress, the Stop Capture button will be available and will stop the current
capture.
7.4 Pause
When a capture is in-progress, the Pause button will be available and will pause capture. This is
useful if a cloud is passing over the object of interest. Pause only works for DirectShow cameras in
SharpCap 2.9, but will be available for a much wider range of cameras in 2.10.
7.5 Snapshot
The Snapshot button will capture the current image as seen in the display area to a PNG or FITS file.
The location of the captured file appears in the Notification Bar below the Tool Bar, for example:
<ALT> <A> can be used as a hot key combination to initiate a Snapshot.
Page 31 of 157
SharpCap 2.9 User Manual
7.6 Live Stack
This button initiates the Live Stack process. The functionality is identical to choosing Tools > Live
Stack. See Live Stacking for a full description of the tool.
<ALT> < L> can be used as a hot key combination to initiate Live Stack.
7.7 Object Name
Selecting Object Name in the main toolbar allows a pre-defined object to be selected and used as
part of the capture folder hierarchy.
A new name can also be typed here to represent the current object of interest – such as M42 or
Orion Nebula.
Subsequent captures would be saved in a sub-folder called M42 (or Orion Nebula) under the default
capture folder. Objects added here will not persist across SharpCap restarts. To become
permanent, the object must be added via File > SharpCap Settings > General tab.
This tool is convenient for self-documentation purposes (in the capture folder name hierarchy)
during an imaging session. For example, names such as ‘M42 CLS filter’ and ‘M42 f6.3 reducer’ can
be created to identify equipment used for a capture.
7.8 Preview FX (effects)
The Preview Effects, FX, dropdown contains the options shown below.
When an FX option is chosen, the FX Selection tool from the tool bar becomes active.
Page 32 of 157
SharpCap 2.9 User Manual
A red rectangle, which can be dragged and resized, appears on the image. In this way, the
special effect can be applied only to the
selected area.
Preview Effects (FX) will apply only to the display and not affect the captured data.
This tool can also be used with the Image Histogram and Calculate Focus Score tools to limit an
action to a section of the image.
7.8.1 None
No effects are applied to the image.
7.8.2 Highlight Over Exposed
Any part of the image which is deemed to be over exposed is highlighted in red. In this graphic,
notice the red highlighted areas.
This is a more extreme example using the moon – the camera exposure setting needs to be reduced
to remove the red highlighted area.
7.8.3 Image Boost
Image Boost is useful when trying to find fainter objects. The image will appear slightly grainy as
noise is introduced.
Page 33 of 157
SharpCap 2.9 User Manual
7.8.4 Image Boost More
Image Boost More applies a greater boost to the image, allowing even fainter objects to be revealed.
An increase in graininess is to be expected.
7.8.5 Frame Stack (3)
With Frame Stack (3), 3 images are stacked. This effect can assist when looking for fainter objects.
Stacking when this option is applied does not attempt to align new images with previous images in
the stack.
7.8.6 Frame Stack (5)
With Frame Stack (5), 5 images are stacked. This provides a further boost to brightness when trying
to locate faint objects.
Page 34 of 157
SharpCap 2.9 User Manual
7.8.7 Frame Stack (10)
With Frame Stack (10), 10 images are stacked.
7.8.8 RGB Align
RGB Align can be used for planetary imaging when, due to atmospheric conditions, the object being
imaged has colour distortion at the edge. In this extreme example, note the red on one side and the
blue on the other, caused by the varying refraction of colours of light as they enter the atmosphere.
Use this option to adjust the red/blue values to obtain a good image on screen to ensure best focus
when preparing to capture. The right-hand image shows the same view of Jupiter with the colour
channels aligned.
RGB Align applies only to the previewed image, it does not affect the captured data. Other
programs, such as Registax, allow re-alignment of RGB channels in the final captured images.
Since the RGB align only affects the image as displayed on screen, its main use is to correct for RGB
misalignment to allow a better judge of focus quality to be obtained, or for live broadcasting of
planetary imaging.
Page 35 of 157
SharpCap 2.9 User Manual
7.8.9 Stop Motion Video
This option will terminate an in-progress video capture. A basic tool to allow stop motion frames to
be captured from any camera supported by SharpCap.
7.9 FX Selection Area
The FX Selection Area tool creates a red selection rectangle on the image which can be dragged and
re-sized. This selected area is used when applying special effects (FX) or when using the Calculate
Focus Score tool.
The FX Selection Area tool can also be used to investigate the histogram of a reduced area when
using the Image Histogram tool.
7.10 Reticule Overlays
The Reticule Overlay tool has 3 options.
By repeatedly clicking the icon located in the Tool Bar, the display area will cycle through the reticule
options. The reticule can be selected directly by using the drop-down menu to the right of the
button.
•
•
•
The reticule can be ‘grabbed’ by the mouse and moved around in the display area.
When the reticule is displayed, the centre point can be moved by clicking anywhere on the
preview display.
Dragging or clicking with the right mouse button instead will adjust the orientation or size of
the reticule.
7.10.1 No Reticule
The graphic is cleared from the image. This is the default.
7.10.2 Crosshairs
A crosshair graphic is imposed over the image in the display area. This can be used to facilitate
accurate mount alignment using a camera rather than an eyepiece.
Page 36 of 157
SharpCap 2.9 User Manual
7.10.3 Circle
A circular graphic is imposed over the image in the display area. This can be used to facilitate
accurate mount alignment using a camera rather than an eyepiece. The rings can also be used to
assist with collimation.
7.11 Zoom
The Zoom tool gives the ability to zoom in or out of the image in the Capture Display Area.
This feature can be used to:
• Zoom in when searching for fainter objects.
• Zoom in when trying to place the FX Selection Area over a
single-star when using the Calculate Focus Score tool.
• Zoom in when trying to accurately set the Black Level % when
using the Calculate Focus Score tool.
• Zoom out to reduce the image when Live Stack or Image
Histogram are in use.
• Zoom out to reduce the image size displayed when capturing
at higher camera resolutions.
•
•
Zoom has a range of 16% - 800%.
Auto zoom is a sensible working setting for most purposes – it
will fit the image to the screen space available.
7.12 Image Histogram
A correctly shaped Histogram is a key requirement to producing quality images.
Clicking the Image Histogram icon in the Tool Bar:
Page 37 of 157
SharpCap 2.9 User Manual
will display the Image Histogram in the Work Area of the Main Screen.
See The Histogram for a full description and examples including information on logarithmic versus
linear scales and the impact of solar/lunar/planetary/deep sky/ROI on the shape of a histogram.
7.13 Calculate Focus Score
SharpCap has a several options to help acquire focus on targets (possibly one of the most
challenging aspects of astrophotography). The tools are particularly powerful if an ASCOM focuser is
configured in SharpCap.
Focus assistance is started by selecting the Calculate Focus Score icon from the Tool Bar.
Focus tools for planetary or surface targets:
•
•
•
Contrast (Edge) Detection
Contrast (Brightness Range) Detection
Fourier Detail Detection
Focus tools for stars or other point sources:
•
•
•
FWHM Measurement
Multi-Star FWHM Measurement
Bahtinov Mask
See Focusing for a full description including introductory materials and examples.
Page 38 of 157
SharpCap 2.9 User Manual
8 Camera Control Panel
The capabilities and available controls of the active camera are displayed in the Camera Control
Panel. The groups and controls displayed can vary depending on:
•
•
The manufacturer of the attached camera.
The model of camera (even from the same manufacturer)
See Camera Controls for a full description. Common camera controls are described first followed by
descriptions of manufacturer specific camera controls.
•
The controls are grouped logically and each group can be expanded/closed as required.
•
The control groups can be grabbed with a mouse and the order re-arranged to suit user
preferences. To reset the order to default, use Options > Reset Control Order from the main
menu.
•
The title bar of the panel can be used to drag the panel out of the main SharpCap form, for
example to place it on a second monitor.
The pin icon can be used to Auto Hide the Camera Control Panel, leaving it docked at the
side.
•
Page 39 of 157
SharpCap 2.9 User Manual
•
A new value can be typed in for many controls. Any camera controls showing a numeric
value (gain, exposure, brightness and many others) can be changed by typing a new value
into the display box and pressing <Enter> or <Tab>. If a value typed in is out of range, the
value will be ignored.
8.1 Capture Profiles
A Capture Profile is a collection of camera settings stored in a text file. Various profiles can be
loaded to have instant access to known collections of settings for different targets and cameras.
•
•
•
•
Load – loads the values from the capture profile currently selected in the drop down and
applies them to the camera controls.
Save – takes the current values of the camera controls and writes them to the profile
currently selected in the dropdown (overwrites the profile).
New – creates a new profile from the current camera control values.
Set Default – by selecting a profile and clicking Set Default, the displayed profile will become
the default for the camera when SharpCap next opens the camera.
A new Capture Profile can be created by clicking New, entering a meaningful profile name, followed
by OK.
The available stored Capture Profiles can be accessed from the drop down:
Page 40 of 157
SharpCap 2.9 User Manual
Note, changing the selected item in the drop down of profile names doesn't do anything by itself, it
just changes the profile used if Save or Load is pressed.
8.2 Capture Format and Area
The controls in this section allow management of the resolution, bit depth, colour space and binning
of the camera as well as the save format for any captured images.
An alternate Colour Space can be chosen if required.
When the output format is set to Auto, SharpCap will chose the most appropriate save format for
capture files depending on the colour mode chosen and the exposure length.
•
•
•
•
Exposures of less than 5s will be saved into a video format.
Exposures of 5s or more will be saved as individual frames.
RGB and Mono at 8 bits per pixel will be saved to AVI or PNG.
16 bit per pixel or RAW modes will be saved to SER or FITS.
8.3 Camera Controls
The controls in this section allow management of the exposure, gain and other mostly hardware
related features of the camera.
Page 41 of 157
SharpCap 2.9 User Manual
8.4 Image Controls
The controls in this section allow application of basic image processing such as brightness, gamma
and contrast to the images being captured by the camera. The range of controls available is
determined by the camera manufacturer/camera driver author.
SharpCap can add a timestamp showing the date and time to captured frames from many cameras.
Supported cameras include ZWO, QHY, Altair and iNova cameras, and DirectShow cameras when
capturing in MONO8 or RGB24 format.
Adding a timestamp to DirectShow cameras capturing in compressed formats (such as I420, MJPG,
YUY2) is not currently supported as SharpCap would need to decompress, alter and recompress each
frame.
8.5 Pre-processing
Astro cameras can have a dark frame applied by selecting one here. Webcams and frame grabber
devices can only apply a dark frame in the Live Stacking options.
Page 42 of 157
SharpCap 2.9 User Manual
8.6 Display Controls
These controls allow adjustment of the brightness, contrast and gamma used to display images,
allowing faint detail to be brought out easily. They provide similar effect to the Image Boost options
in the FX dropdown but with finer control.
For all supported cameras (except DirectShow cameras), SharpCap includes a Display Controls group
in the control panel. Any changes made in the Display Controls section only affect how the images
are displayed on screen – there will not be any changes made to the images saved to any capture
files.
8.7 Testing Controls
The testing Controls group is specific to the two test cameras included with SharpCap. The controls
allow for the simulation of atmospheric conditions.
8.8 Other Controls
These are manufacturer dependent, examples include:
•
•
•
Telescope controls.
Thermal controls such as fan on/off.
GPS settings.
Page 43 of 157
SharpCap 2.9 User Manual
9 Capturing Videos and Images
Video and image capture can be started from the Capture menu or the equivalent buttons in the
toolbar.
9.1 Start Capture
The Start Capture menu item or toolbar button allows a custom capture limited either by number of
frames or time to be started.
Capture Limits Explained
•
•
•
Two files will be created – a single frame
PNG or FITS, together with the camera
settings TXT.
Upon completion of the capture,
information will be displayed in the
Notification Bar.
The files will be stored in the default
capture folder.
Page 44 of 157
SharpCap 2.9 User Manual
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Two files will be created – an AVI or SER,
together with the camera settings TXT.
Note if a still file format is selected in the
‘Output Format’ control, multiple still
image files will be created in a single folder
instead of a single video file.
Upon completion of the capture,
information will be displayed in the
Notification Bar.
The files will be stored in the default
capture folder.
The capture will continue until the Stop
Capture button in the tool bar is clicked.
Two files will be created – an AVI or SER,
together with the camera settings TXT.
Note if a still file format is selected in the
‘Output Format’ control, multiple still
image files will be created in a single folder
instead of a single video file.
Upon completion of the capture,
information will be displayed in the
Notification Bar.
In this example, the capture file will
contain 5 frames.
The files will be stored in the default
capture folder.
A time limit can be set using HH:MM:SS.
In this example 30 seconds is the limit set
for the capture.
Two files will be created – an AVI or SER,
together with the camera settings TXT.
Note if a still file format is selected in the
‘Output Format’ control, multiple still
image files will be created in a single folder
instead of a single video file.
Upon completion of the capture,
information will be displayed in the
Notification Bar.
In this example, the capture file will be a
30 second video.
The files will be stored in the default
capture folder.
Page 45 of 157
SharpCap 2.9 User Manual
•
•
•
•
•
•
•
•
This repeats the capture defined in the
capture limit section above.
Note this option cannot be activated when
the capture limit set above is ‘Unlimited’.
A sequence of captures, with an interval
between them, can be initiated.
In this example, 3 captures will be taken,
with an interval of 10 seconds between
them.
Six files will be created – 3 AVI or SER,
together with 3 camera settings TXT.
Upon completion of the capture,
information will be displayed in the
Notification Bar.
In this example, the capture files will be a 3
x 10 second videos.
The files will be stored in the default
capture folder.
Once the capture options have been set, press the Start button to begin the capture or press the
Cancel button to abort.
With large numbers of frames or extended time sequences it is advisable to use a guided telescope.
During a capture, the progress will be shown at the right-hand end of the Status Bar (bottom right of
the screen).
Actual/Total frames and an estimated finishing time are displayed for the duration of the capture.
When the capture is complete, information about the status, location and name of the captured file
is displayed in the Notification Bar below the Tool Bar.
The blue text in the Notification Bar is clickable and will go directly to the capture file/folder.
9.2 Stop Capture
Once a capture has been initiated, the Stop Capture option becomes available – this will stop the
current capture immediately. Note if a sequence of captures is in progress it will only stop the
current capture, not cancel the sequence. The whole sequence can be cancelled using the button in
the notification bar that appears while waiting for the next capture in the sequence.
9.3 Delete Last Capture
Once a capture has been completed, the option to Delete Last Capture becomes available. A
confirmation dialogue window is shown, which is useful if a capture is taken accidentally or if
something goes wrong during a capture.
Page 46 of 157
SharpCap 2.9 User Manual
9.4 Open Capture Folder
Open Capture Folder opens a File Explorer window at the location where captures are currently
being saved. In a default configuration, this would normally be:
Desktop\SharpCap Captures\YYYY-MM-DD
9.5 Capture Dark
This menu item launches the SharpCap dark frame capture assistant – see Capturing and Using Dark
Frames.
Page 47 of 157
SharpCap 2.9 User Manual
10 Camera Basics
10.1 Colour Spaces Explained
A colour space describes how the image data is stored for each frame captured from a camera. The
details of a colour space indicate:
•
•
•
Whether the image data is colour or monochrome.
How many levels of brightness are measured.
Whether the image data is compressed or not.
The number of brightness levels that are available in an image is often described using the term ‘bit
depth’. The bit depth is the number of bits needed to store the full range of brightness levels in the
image. For instance, an image that has:
•
•
•
•
256 brightness levels will have a bit depth of 8
1024 brightness levels will have a bit depth of 10
4096 brightness levels will have a bit depth of 12
65536 brightness levels will have a bit depth of 16.
10.2 Uncompressed Colour Spaces
The colour spaces listed in this section are uncompressed and lossless – meaning that they do not
reduce the quality of any images being captured. All specialist astronomy cameras and some
webcams will offer the option of uncompressed colour spaces.
10.2.1 RGB24
This is the default colour space for a colour image – 3 bytes are used for each pixel (one for each of
the red, green and blue channels). The one byte used for each channel means that there are 256
possible values for each colour (from 0 to 255).
Pros:
•
•
•
Cons:
•
•
•
•
Simple to use and simple post-processing.
Images should look correct when viewed in any application.
Camera based adjustments such as white balance, gamma, brightness and contrast
are available (although these are usually performed in software on the PC).
Files are large as they are typically 3 bytes per pixel.
Bit depth limited to 8 bits.
Debayering (turning the raw image to full colour) is performed by the camera driver
typically using a simple but fast algorithm.
Adjustments like gamma, brightness and contrast lead to data loss when performed
as they happen in digital space.
10.2.2 RGB32
This is an alternative option for a standard colour image. Instead of 3 bytes, 4 bytes of space are
used per pixel, although one of the bytes is unused. Files saved in this format will be larger than the
same file saved in RGB24, but will have absolutely no difference in image quality.
Pros:
•
•
•
Cons:
•
Simple to use and simple post-processing.
Images should look correct when viewed in any application.
Camera based adjustments such as white balance, gamma, brightness and contrast
are available (although these are usually performed in software on the PC).
Files are large as they are typically 4 bytes per pixel.
Page 48 of 157
SharpCap 2.9 User Manual
•
•
•
Bit depth limited to 8 bits.
Debayering (turning the raw image to full colour) is performed by the camera driver
typically using a simple but fast algorithm.
Adjustments like gamma, brightness and contrast lead to data loss when performed
as they happen in digital space.
10.2.3 MONO8 (also Y800)
This is the basic monochrome colour space, using one byte per pixel, storing a single brightness
value between 0 and 255.
Pros:
•
Cons:
Smaller file size (1 byte per pixel), ideal for monochrome targets (narrowband filters,
moon).
The following cons apply only when capturing in MONO on a colour camera.
•
Processing to produce mono on a colour camera involves a debayer process to
produce a colour image and then that is made monochrome, so the following cons
for RGB apply:
o Debayering (turning the raw image to full colour) is performed by the
camera driver typically using a simple but fast algorithm.
o Adjustments like gamma, brightness and contrast lead to data loss when
they are performed as they happen in digital space. It may be better to
capture as RAW8/12 and then make the final processed image
monochrome.
10.2.4 MONO16
This is a monochrome colour space which uses 2 bytes per pixel, allowing for 65536 different
brightness values per pixel. Note that many cameras that offer this colour space do not have the
ability to create the full range of 65536 values – for instance some cameras may have the ability to
create only 1024 different values (10 bit) or 4096 different values (12 bit). In these cases, the values
the camera produces are stretched to fill the entire range.
Pros:
•
Cons:
•
•
Larger range of levels in the output, so a bigger range of brightness can be
represented in a single image
Larger file size (2 bytes per pixel)
No gain in actual image quality if the frames being captured are visibly noisy (just
recording the noise in more detail)
The following cons apply only when capturing in MONO on a colour camera.
•
Processing to produce mono involves a debayer to produce a colour image and then
that is made monochrome, so the following cons for RGB apply:
o Debayering (turning the raw image to full colour) is performed by the
camera driver typically using a simple but fast algorithm.
o Adjustments like gamma, brightness and contrast lead to data loss when
they are performed as they happen in digital space. It may be better to
capture as RAW8/12 and then make the final processed image
Page 49 of 157
SharpCap 2.9 User Manual
monochrome.
10.2.5 RAW8
Colour cameras do not detect all three colour channels (red, green and blue) at each pixel – in fact
each pixel only detects light of a single colour. The colours are arranged in a grid fashion – usually
called a Bayer matrix – which looks like this (the graphic is a GRBG Bayer matrix):
Almost all colour cameras capture their colour data in this way. A technique called ‘debayering’ is
used to generate a full set of red, green and blue values at each pixel to give a full colour image.
When using an RGB colour space, this debayering process occurs either on the camera or in its driver
software.
When capturing in a raw colour space such as RAW8, the original values of the individual red, green
and blue pixels are captured by SharpCap. SharpCap has its own debayering code, so the image as
seen on the screen will still be in colour, but saved files will appear to be monochrome with a slight
grid pattern visible at the pixel level unless they are opened in software that is capable of
debayering. Suitable software for this includes PIPP, Registax, AutoStakkert and Deep Sky Stacker.
Saved files captured in RAW8 format will consume only 1 byte per pixel, so they have the great
advantage over RGB files of being much smaller. Additionally, a file that is saved in RAW format can
be debayered by appropriate processing software using a slower but higher quality algorithm than
those typically used in camera drivers.
There are four varieties of the RAW8 colour space, depending on where in the green/red/blue grid
the top-left pixel of the camera sensor starts. These variations are named after the top left four
pixels on the camera sensor
•
•
•
•
RGGB
BGGR
GRBG
GBRG
For instance, RGGB means that the left hand two pixels of the top row are red and green and the left
two pixels on the second row are green and blue respectively.
In general, SharpCap knows which pattern a camera uses in RAW mode and will select the correct
pattern automatically, however if the wrong pattern is selected automatically then manually choose
the correct pattern by adjusting the value of the ‘Debayer Preview’ control. This control can be used
to turn off the debayering function if desired. The easiest way to find the correct pattern is to view a
red object or light with the camera – only the correct pattern will show a red image.
Page 50 of 157
SharpCap 2.9 User Manual
Note that even when SharpCap is debayering the image being viewed on screen, images saved to
any capture files are still in RAW format.
Pros:
Cons:
•
•
•
•
•
•
•
Exact data that comes off the camera sensor with no post-processing.
Post-processing (including debayering) can be done later at a higher quality.
File size is small (1 byte per pixel)
Smaller range of applications that can work with the output files.
Post-processing is more complex.
Output files may appear to have 'chessboard' effect if opened in applications that
don't understand raw formats.
Bit depth limited to 8 bits.
10.2.6 RAW16
The RAW16 colour space is a raw colour space for bit depths of up to 16 bits per pixel. On some
cameras, this will be labelled as RAW10 or RAW12 to give a more accurate description of the true bit
depth available from the camera. Saved files in the RAW 16 colour space use 2 bytes per pixel.
Pros:
•
•
•
Cons:
•
•
•
•
Exact data that comes off the camera sensor with no post-processing.
Post-processing (including debayering) can be done later at a higher quality.
Higher bit depth may give more information and more dynamic range if images are
low noise.
Smaller range of applications that can work with the output files.
Post-processing is more complex.
Output files may appear to have 'chessboard' effect if opened in applications that
don't understand raw formats.
Files are larger (2 bytes per pixel).
10.3 Compressed Colour Spaces
Many webcams only offer compressed colour spaces. While these reduce the size of capture files
they also mean that some detail of the image is lost. Unless creating small capture files it is very
important compressed colour spaces should be avoided if possible.
10.3.1 YUY2 / YUV
These are just two names for the same colour space. In these colour spaces, brightness information
is stored at every pixel, but colour information is shared between two adjacent horizontal pixels.
Since the colour information consists of two bytes of information (hue and saturation), this means
that overall 2 bytes are used per pixel in this colour space. (http://www.fourcc.org/yuv.php)
10.3.2 I420
In this colour space, brightness is still stored at every single pixel, but colour information is shared
between a block of 4 pixels (2x2). This means a total of 1.5 bytes are used per pixel in this colour
space.
10.3.3 MJPEG
In this colour space, each frame is stored as a compressed JPEG image. This leads to a much smaller
capture file than any other colour space, but can lead to significant compression artefacts in the
images. The level of compression is set by the camera or camera driver and cannot be adjusted.
Page 51 of 157
SharpCap 2.9 User Manual
10.4 Choosing the Correct Colour Space
In general, the following guidelines will help choose the correct colour space:
•
•
For a colour camera prefer RAW colour spaces if available to RGB colour spaces.
If no RAW colour spaces, prefer uncompressed RGB to compressed colour spaces unless
small output files are very important.
If having the option of choosing a higher bit depth (RAW10,12,16 or MONO16), only do so if there
can be see no noise that changes from frame to frame in the corresponding 8-bit mode. If there is
visible noise in 8 bit, then all that a higher bit depth will do is measure and store more detail of the
noise (and make output files twice as big). This means that higher bit depths are only useful at low
gains.
10.5 Capture Formats Explained
10.5.1 AVI
The AVI file format is a video file format. While the AVI file format is commonly used, and can be
read by many different applications, it is unfortunately a complex file format which can store video
data in many ways. This means that sometimes certain applications may have difficulty reading
certain AVI files, while the same files work correctly with other applications or on other computers.
In general, however, AVI files in either MONO or RGB colour spaces will work correctly on any
software on any system.
AVI files can only save video format at a bit depth of up to 8 bits per colour channel, so capture to
AVI is not available when using a camera in a higher bit depth mode.
While AVI files can be used to save captures in RAW format, processing software will not recognize
this automatically and will generally show a monochrome image with a pixel grid visible if the
appropriate Bayer pattern is not specified manually.
PIPP - Planetary Imaging PreProcessor (commonly referred to as PIPP) is useful software for dealing
with troublesome AVI files and to stabilise the frames of a video that are too jumpy for stacking
software to handle.
Pros:
Cons:
•
•
•
•
•
•
Can be viewed in almost any video playback software.
File format is complex and has many sub formats.
Correct playback may depend on other software and codecs installed on the
machine.
Errors may be subtle and difficult to solve.
8-bit only.
Mono and RAW saved in AVI may appear upside down due to limitations of the file
format.
10.5.2 SER
The SER file format is another video file format that has been designed specifically for astronomy
capture. SER files cannot be read, viewed or processed by as many different applications as AVI files
but there tend to be far fewer seemingly random issues caused by incompatibilities as the file
format is far simpler than the AVI file format.
The SER format can be used to save videos in the RGB, Mono and RAW formats and can be used to
capture at both 8 bits per pixel and up to 16 bits per pixel bit depth.
Page 52 of 157
SharpCap 2.9 User Manual
When capturing in a RAW format, the details of the sensor Bayer pattern is stored in the SER file,
meaning that most processing and viewing software will automatically read this information and
correctly debayer the raw image data to a colour image.
Additionally, a timestamp for each captured frame is stored in the SER file, which is often useful for
later image processing.
A SER Player application can be downloaded from the PIPP website.
Pros:
•
•
Cons:
•
•
•
•
•
Simple file format with few variations - applications tend to work correctly with it or
not at all.
SER file is written with the Bayer pattern of the camera which simplifies postprocessing for RAW captures.
Supports bit depths of 8 bits per pixel and up to 16 bits per pixel.
Each frame in the file is timestamped exactly.
Supports Mono, RAW and RGB captures.
Less post-processing applications support SER format but the ones which are most
used, listed below, all accept SER format:
o AutoStakkert AS2 (stacking).
o Registax 5 and 6 (stacking and wavelet sharpening).
o PIPP (preparing the video files for processing).
Interpretation of the SER standard is somewhat different so sometimes the program
needs help to select the correct colour space if not automatically recognized.
10.5.3 PNG
PNG files are standard image files for capture of single frames. Almost any image processing or
viewing software will be able to open a PNG file, making them easy to work with.
Still images in any format (a bit depth of 8 or 16 bits, colour, monochrome or RAW) can be stored in
a PNG file. It is worth noting however that many image processing applications do not deal correctly
with PNG files with a bit depth of 16 bits – often they will drop the bit depth to 8 bits as they load
the file, throwing away detail.
When saving RAW images to a PNG file they are saved as monochrome PNG files and image
processing and viewing software will display them as monochrome showing a pixel grid pattern
unless correctly set up to debayer the images.
Pros:
Cons:
•
•
•
•
•
Can be loaded into almost any graphics application
Handles 8-bit to 16-bit depths and mono or colour images.
Many imaging applications may discard detail from 16 bit PNG files when loading
them.
RAW images saved in PNG will appear monochrome with a checkerboard pattern
and may need additional manual settings in post-processing to ensure correct
debayering.
SharpCap can only re-load 8 bits of data from PNG files, even when loading 16 bit
saved files.
Page 53 of 157
SharpCap 2.9 User Manual
10.5.4 FITS
The FITS file format is a highly flexible but specialised format that is often used for storing high bit
depth still images. While the FITS format can store images at a bit depth of 8 bits, it is usually better
to choose PNG for that case.
Since FITS is a specialised file format, there are less applications that can process FITS files to choose
between – certainly most image viewing and editing applications which can quite happily work with
PNG files will not be able to open FITS files. There are however applications such as Deep Sky
Stacker or FITS Liberator that can be used to process and view FITS files. [Note: only use FITS
Liberator on a copy of captured data as the software can change the data without warning (thanks
to Gary Palmer for that advice).]
Pros:
Cons:
•
•
•
•
•
•
•
•
Supports 8 bit and greater bit depths.
Supports mono, colour and raw images.
Image data, such as exposure, is stored in the file and some applications will read
this data.
SharpCap can load 16 bits of data from FITS files when loading dark frames.
Can only be opened by a limited number of applications.
Some applications require additional plugins to open this file type.
File format is very complex and flexible, so files may display incorrectly in some
applications and correctly in others.
Slower to save to than other file formats, so not suitable for high frame rates.
Page 54 of 157
SharpCap 2.9 User Manual
11 Camera Controls
Generic camera controls are described below in Common Camera Controls.
Subsequent subsections describe features specific to individual camera manufacturers. The same
functionality may have different names across manufacturers. Different models from the same
manufacturer may have differing features. The manufacturers are described in alphabetic order.
11.1 Common Camera Controls
The controls listed below are generally expected to be available across a wide range of cameras from
different manufacturers, although not all cameras will have every control listed in this section.
These controls are to be found in the Camera Control Panel (which by default is shown to the right of
the main camera image).
11.1.1 Capture Format and Area
Capture Format and Area
Colour Space
•
•
Capture Area
•
•
•
ROI Position (pan/tilt)
•
•
The colour space control determines the image format each
frame is captured in. In general, there are four categories of
colour spaces
o Monochrome
o Colour
o Raw
o Compressed
See Colour Spaces Explained for more detail on the colour space
to choose and the implications of each choice.
This controls the size (in pixels) of each frame captured.
For most cameras, the choice of a smaller capture area selects
capture of a subarea of the full sensor area – this is often termed
ROI (region of interest) capture.
As well as giving smaller saved files, selecting a smaller capture
area often gives a higher frame rate.
When a smaller capture area is selected, it is usually also possible
to choose which region of the sensor is used – selecting the
appropriate Region of Interest (ROI).
Only shows if the selected ROI is smaller than the maximum.
Page 55 of 157
SharpCap 2.9 User Manual
Binning
Output Format
Debayer Preview
See Binning below further information.
• Output format allows the choice of the format any captured files
will be saved in. The options for capture format can be found in
Capture Format and Area. The following rules apply:
• For 'Snapshot' (single frame) captures, one of the still capture
formats (PNG or FITS) are always used, even if the selected
output format is a video format (AVI or SER). If the output
format is a still file format the selected format is used.
• For video captures, the selected format is always used. If a
still file format is selected each frame will be saved to a
separate file.
[Note: When 'Auto' is enabled the preferred output file formats
specified in the settings dialog are used (providing the preferred
format is compatible with the type of image being captured – for
instance 16-bit depth images cannot be saved to SER format).]
• Only shows for RAW colour spaces.
• Allows the user to choose to debayer (convert to colour) or not
the raw image for display.
• Does not affect the data saved to file.
• As well as switching the debayer function on and off it is possible
to override the Bayer pattern used if, for some reason, the wrong
pattern is selected automatically.
11.1.1.1 Binning
Binning is a technique used to improve the signal-to-noise ratio of an image at the expense of
reducing the resolution. Binning works by taking the value of 2 or more neighbouring pixels on the
sensor and either adding or averaging them to produce the value for a single output pixel. Binning is
usually 'symmetric' - meaning that the same number of pixels are averaged over in each direction.
For instance, a binning value of '2x2' or just '2' means that a 2 by 2 block of sensor pixels are used to
make each pixel in the final image – this will reduce the resolution of the final image by a factor of 2,
but also increase the signal-to-noise ratio (S/N ratio) of the image by a factor of 2.
As an example, with a 1280x960 sensor, using 2x2 binning will give an output image of 640x480.
Using 4x4 binning will give an output image of 320x240.
A binning value of '1' or '1x1' means that no binning is being applied.
It is important to note that some cameras add pixel values when binning (meaning that the image
will get brighter when binning is turned on), while other cameras average the values (meaning that
the image doesn't get brighter, but the noise reduces instead). In both cases, the same increase in
S/N ratio is achieved in the final image – if a brighter image is required and the camera averages
then just turn up the gain – the result being the same as if the camera had added pixels.
Page 56 of 157
SharpCap 2.9 User Manual
11.1.1.2 Additive Binning
Unbinned (width 2x, height 2y)
Binned 2x2 (width x, height y)
Additive binning – no other changes were made to camera settings between the unbinned and
binned images. Applying the 2x2 binning halves the size of the captured image and brightens the
image by a factor of four. Note that a considerable level of noise is visible in the brighter right hand
section of the image in both frames.
11.1.1.3 Averaging Binning
Unbinned (width 2x, height 2y)
Binned 2x2
(width x, height y)
Binned 2x2 with extra gain
(width x, height y)
Averaging binning – no other changes were made to camera settings between the unbinned and
binned images. Applying the 2x2 binning halves the size of the captured image but does not
brighten the image in this case. However, looking closely at the bright area on the right-hand side of
the image shows that applying the binning has significantly reduced the noise in this area (and across
the rest of the frame). Increasing the gain further does brighten the binned image producing a
similar image to the additive binning result both in terms of image brightness and noise level.
Page 57 of 157
SharpCap 2.9 User Manual
11.1.2 Camera Controls
Camera Controls
Exposure
•
•
•
•
•
•
Gain
•
•
Frame Rate Limit
•
•
Flip
•
Temperature [Read Only]
•
Exposure controls the length of time that the camera collects
photons for each frame.
Longer exposures allow more photons to be collected and will
therefore give brighter images.
For most cameras, the selection of a longer exposure can limit
the frame rate. For instance, setting an exposure of 100ms
(1/10s) will limit most cameras to a frame rate of 10 frames per
second.
Each camera will have its own limits for the length of exposure it
allows.
Some cameras (particularly webcams) may report incorrect
ranges of allowable exposures to SharpCap.
The LX checkbox in the exposure control has only one effect – it
changes the range of the exposure slider from minimum
exposure to 5s (LX unticked) to 0.5s to maximum exposure (LX
ticked). This is necessary because for cameras with a very wide
possible exposure range it becomes difficult to adjust the
exposure accurately if the slider range runs all the way from
0.01ms to 1000s.
The gain control acts as an amplifier for the signal received by the
sensor.
Turning up the gain will increase the brightness of an image
without needing to increase the exposure duration, but at the
cost of the making the image noisier.
Limits the rate at which frames are processed by SharpCap, even
if the camera is creating frames at a higher rate.
This affects the rate at which frames are saved to any capture file
and the rate at which the UI is updated.
Apply a horizontal or vertical (or both) flip to an image to correct
its orientation.
The current temperature of the camera sensor. Note that if the
camera has more complicated thermal controls (for instance a
Page 58 of 157
SharpCap 2.9 User Manual
Peltier cooler), the current temperature will appear with those
controls in the Thermal Controls section.
11.1.3 Image Controls
Image Controls
Gamma
•
•
•
•
Contrast
•
Brightness
•
•
Timestamp Frames
•
•
•
Neutral gamma is 1.
Correctly interpreted, gamma of less than 1 will boost the shadows
and mid tones, gamma greater than 1 will lower the mid tones and
highlights.
Some applications and cameras treat gamma the opposite way
around – increasing gamma boosts the shadows.
See http://www.orpalis.com/blog/color-adjustments-brightnesscontrast-and-gamma/ for more details on gamma, contrast and
brightness.
Increasing contrast will typically make the dark pars of the image
darker and the bright parts brighter.
Sometimes this can help pull out detail in the image.
Increasing brightness will typically make the image brighter by the
same amount.
This can help pull out detail in the darker regions of the image.
Applies a UTC timestamp in the top left corner of the frame.
As well as the visible timestamp a machine-readable timestamp is
embedded into the first 8 bytes of the pixel data of the frame.
The machine-readable timestamp is a 64-bit integer that is the number
of 100ns intervals since midnight on 1st Jan 0001 (see
https://msdn.microsoft.com/enus/library/system.datetime.ticks(v=vs.110).aspx
White balance
for defaults)
See White Balance below.
White Balance – Images shown from colour cameras can frequently show incorrect colours. This can
be due to a range of reasons, such as:
•
•
One colour (often green or red) being more sensitive to light than the other colours.
The type of illumination the image is being taken under – for instance tungsten, LED or
fluorescent lights for non-astro images.
Different cameras have different controls to enable colour balance to be adjusted to give images
showing the correct colours.
Page 59 of 157
SharpCap 2.9 User Manual
Although these controls differ in detail they all effectively allow the brightness of the colour
channels to be adjusted relative to each other to correct the colour cast in the image.
Some cameras offer an auto white balance option – these often work well for ordinary images but
can sometimes be confused by astro images, so should be used with caution.
Use the histogram control while adjusting the white balance and other image controls such as
gamma, contrast and brightness – if it is noticed the histogram trace for any of the colour channels
has gaps (i.e. levels with zero count appear in the middle of the histogram – see graphic below), it
probably means the white balance (or other) adjustment is being done in software on the PC rather
than in hardware on the camera. Histograms such as the one below indicate data is being lost.
In this case, it is best to set the white balance back to default (remove the gaps in the histogram) and
to correct the colour balance after stacking. This will avoid the data loss caused by applying digital
white balance correction in SharpCap.
11.1.4 Pre-processing
Preprocessing
Subtract Dark
•
Subtracts the selected dark frame image from each frame
captured by SharpCap, allowing artefacts such as amp glow and
dark noise to be reduced.
[Note: the dark frame is subtracted before any other processing of
the frame (such as live stacking or any FX effects) and the subtraction
of a dark frame affects the saved file.]
11.1.5 Display Controls
Display Controls
Page 60 of 157
SharpCap 2.9 User Manual
Display Gamma
•
Display Contrast
•
Display Brightness
•
Applies a gamma correction to the frame as displayed in the UI
only – changes made here do not affect the data saved to file.
Applies a contrast correction to the frame as displayed in the UI
only – changes made here do not affect the data saved to a file.
Applies a brightness adjustment to the frame as displayed in the
UI only – changes made here do not affect the data saved to a
file.
11.2 Camera Specific Controls
The controls listed below will appear in addition to the common controls listed above.
11.2.1 Altair Camera Controls
SharpCap supports all current models of camera produced by Altair Astro. If the camera is a new
model and not in the Cameras list, please check for an updated version of SharpCap which may
include changes needed to support the camera.
Further information can be found at the Altair Astro website. Drivers, software and technical notes
can be found at the Altair Support website.
Image Controls
White Balance Adjust
Negative
Colour Tint
Colour Temperature
Digital Processing (On/Off)
Camera Controls
Auto Exposure Target
USB Speed
Flip
Performs a single auto adjustment of the image white
balance.
Converts the image to a negative representation (black
becomes white, white becomes black, colours are reversed).
Adjust the green/magenta colour balance of the image –
lower values give a magenta tint to the image, higher values a
green tint.
Adjusts the red/blue colour balance of the image – setting
this value higher will make the image appear redder, setting it
lower will make it appear bluer.
Enables/Disables the digital adjustments to the image in the
Altair Driver.
• When this is switched to 'On', controls like Gamma,
Brightness, Colour Tint, etc. are active.
• When switched off, these controls are disabled. Switching
this to Off may give a small performance boost.
Controls the how bright a frame the auto exposure will aim
for (when enabled). When this is set to a low value the auto
exposure will tend to give an under exposed frame with few
highlights. When set to a high value the auto exposure will
tend to give an over exposed frame.
Controls how much of the USB bus speed the camera will try
to use. Higher values will usually lead to higher frame rates,
but setting this value too high may lead to very low frame
rates, irregular frames or no frames at all.
Allows the orientation of the image to be flipped either in the
horizontal, vertical or both. Not available in RAW modes.
Page 61 of 157
SharpCap 2.9 User Manual
Fan
Allows the Fan to be turned on/off on cameras that have a
fan.
11.2.2 ASCOM Camera Controls
ASCOM cameras have relatively few controls available in SharpCap. Drivers and further information
can be found at the ASCOM Standards website.
There is no guarantee all ASCOM cameras will offer all the controls listed below. For instance, some
ASCOM cameras have no cooler at all and of those with coolers some may offer direct control of
cooler power while others may not.
Camera Controls
Options
Thermal Controls
Actual Temperature
Heat Sink Temperature
Cooler (on/off)
Cooler Power
Target Temperature
Allows the ASCOM configuration dialog for the camera to be shown.
May have additional camera options that can be configured. The
camera is temporarily closed while the dialog is displayed and will
restart when it is closed.
The current temperature of the camera sensor (read only).
The current temperature of the heat sink (if any) in the camera (read
only).
Allows any cooler present on the camera to be turned on or off. If
the cooler is turned on, then the cooling level may be controllable
using one of the two controls listed below.
Allows the percentage power that the cooler runs at to be set.
The temperature that the camera will attempt to cool to (adjusting
the cooler power automatically to achieve this temperature).
11.2.3 Basler Camera Controls
Drivers and further information can be found at the Basler website.
Basler cameras may appear more than once in the Cameras menu:
Page 62 of 157
SharpCap 2.9 User Manual
SharpCap has three separate options for working with Basler Cameras:
1. (LX Mode) suffix – uses the camera's trigger functionality (if present) to take longer
exposures than the camera would normally allow. Only use this mode if taking longer
exposures than those available from the other two options.
2. No suffix – the old code to support Basler cameras. Some functions such as pre-processing
and display controls available with other cameras will not be available. This option is
deprecated and will be removed in a future version. Do not use this option unless having
problems with the Experimental option (below).
3. (Alternate, Experimental) suffix – a newer implementation of the Basler camera that should
have all the modern SharpCap features. This should be the preferred way of working with
Basler cameras if long-exposure functionality is not required. This will become the default
method of working with a Basler camera in a future version.
Basler Specific Controls
Capture Format and Area
Colour Space
Basler cameras use non-standard colour space names for RAW
modes.
•
•
•
FPS
BayerBG8 – equivalent to RAW8 with BGGR Bayer pattern.
BayerRG12 – equivalent to RAW12 with RGGB Bayer
pattern.
Bayer GB12Packed – equivalent to RAW12 with GBBR Bayer
pattern. In packed 12 bit modes, 2 adjacent pixels are
packed into 3 bytes (1.5 bytes each) rather than requiring 2
bytes each in unpacked mode. This may increase frame
rates in some circumstances as it reduces the amount of
data that needs to be transferred from the camera to the
computer.
The number of frames per second that the camera will attempt to
deliver to the computer. When left on auto it will aim for the
maximum possible rate. Note that the frame rate set in manual
mode may not actually be achieved due to factors such as the
exposure being too long or the data rate between the camera and
the computer being insufficient to cover the desired frame rate.
If aiming for a limited frame rate, then setting this to a low value is
better than leaving this at a high value and setting the 'Frame Rate
Limit' control as it should reduce the CPU load on the capture
computer.
Camera Controls
Black Level
Allows the black level to be adjusted. This control should be
adjusted with the camera covered to ensure that both sides of the
black level peak in the histogram are visible and distinct from the
zero level to ensure that black level noise can be averaged out
correctly in stacking. Called offset or brightness on some other
cameras.
Page 63 of 157
SharpCap 2.9 User Manual
Digital Gain
An additional gain that can be applied to the image. Each step
above zero doubles the image brightness but also doubles the noise
levels
Processing Controls (should be Image controls for consistency with other cameras)
Auto White Balance
Automatically adjust the white balance of the image when the
'Adjust' button is pressed.
White Bal (R) [Colour
Controls the relative intensity of the red channel of a colour image.
Modes only]
White Bal (B) [Colour
Controls the relative intensity of the blue channel of a colour image.
Modes only]
White Bal (G) [Colour
Controls the relative intensity of the green channel of a colour
Modes only]
image.
11.2.4 Celestron/Imaging Source Camera Controls
SharpCap should support all Celestron branded Skyris and NexImage cameras (manufactured by The
Imaging Source) as well as Imaging Source branded DMK and DFK cameras.
Drivers and further information can be found at the Imaging Source website and the Celestron
website.
Camera Controls
Focus
Iris
Pan, Tilt and Roll
IR Cut Filter
Image Controls
Colour Enhancement
Highlight Reduction
Denoise
Colour Enable
Sharpness
White Balance
White Bal (R)
White Bal (B)
White Bal (G)
Controls the focus of the built-in camera lens (if available).
Controls the aperture of the built-in camera lens (if available).
Physical controls to pan, tilt and roll the camera if it has motor drive to
allow it to be controlled remotely.
Turn on/off the IR cut filter on cameras equipped with a controllable filter.
Enhance colours in the image.
Reduce the relative brightness of the highlights in the image.
Apply a noise reduction filter to each frame (will also tend to reduce
detail).
Switch colour cameras between colour and monochrome mode.
Apply a sharpening filter to each frame to enhance detail (will also tend to
increase noise).
Controls the relative intensity of the red channel of a colour image.
As for White Bal(R) above, but controls blue.
As for White Bal(R) and (B) above, but controls green channel.
11.2.5 iNova Camera Controls
SharpCap supports a range of iNova cameras.
Drivers and further information can be found at the iNova website.
Camera Controls
Page 64 of 157
SharpCap 2.9 User Manual
Black level
Pixel Clock
Horizontal Blank
In theory, the same as the black level control documented for other makes
(copy from QHY?), in practice does nothing due to a bug in the iNova SDK.
How fast the internal CPU of the camera runs. Higher speeds can give
higher frame rates but sometimes too high a speed will lead to no frames
at all.
How long a delay the camera should apply between reading one scan line
of the image and the next. Usually best left on auto, but manual tweaking
can sometimes improve frame rates, with lower values giving faster frame
rates. As with many of these speed controls, going too far can cause the
frame rate to collapse to zero.
11.2.6 QHY Camera Controls
SharpCap supports a wide range of QHY CMOS cameras, including QHY5L-II, QHY5-III, QHY174, 178,
224, 290, 163 and 183. The cooling features of the QHY ColdMOS cameras are supported as well as
the GPS features of the QHY174-GPS.
Drivers and further information can be found at the QHY website.
Camera Controls
Amp Noise
Reduction
This control is available for some cameras and when activated will reduce
the amount of amp glow created by the camera for long exposures.
In general, it is best to leave this control on the 'Auto' setting as it will
apply the amp glow reduction when appropriate. If amp glow reduction is
enabled manually, this may result in incorrect images for certain exposure
and gain combinations.
Row Noise Reduction This control is available for some cameras and can be adjusted to reduce
banding effects between camera rows.
Offset
Allows the black level to be adjusted. This control should be adjusted with
the camera covered to ensure that both sides of the black level peak in
the histogram are visible and distinct from the zero level. This ensures
that black level noise can be averaged out correctly in stacking.
Speed
Control the transfer speed being used by the camera. May increase frame
rate in some circumstances.
USB Traffic
This controls how fast the camera will try to push data over the USB bus.
Setting a lower value will try to move data faster and give higher frame
rates. Setting a value that is too low can cause:
• dropped frames
• a collapse in frame rate
• or even no frames at all
Use DDR Buffer
Available on some cameras. Turns on/off the use of the internal DDR
buffer on the camera. Using the DDR buffer may improve frame rate and
reduce problems with dropped frames.
Optimize Light Level Allows the sensor on the camera to be optimized for low or bright light
levels.
Filter Wheel
Allows a QHY filter wheel connected via the camera port to be controlled.
Note that a connected filter wheel may not be detected if it is still
initializing when the camera is opened in SharpCap.
Enable Live
Enable live broadcast of the images being shown in SharpCap via the QHY
Broadcast
video broadcast application.
Page 65 of 157
SharpCap 2.9 User Manual
GPS Controls
GPS
GPS Calibration LED
Calibration Start Pos
Calibration End Pos
Enable or disable the built-in GPS functionality on cameras that support it.
The GPS feature allows frames to be timestamped precisely to
microsecond precision. GPS may require the camera to be supplied with
12V power. When GPS is enabled and has a satellite lock the timestamp
for each frame taken from the GPS system is used for the timestamp in
capture settings files and SER file frame timestamps. Without further
adjustment, frame times will be accurate to millisecond levels, but to get
microsecond precision the following controls must be adjusted correctly.
The GPS calibration LED must be turned on to be able to correctly adjust
the following two controls. The camera must also be covered so that the
light from the LED can be seen in the image. Turn up the gain so that the
light can be seen easily.
With the GPS LED on, turn the calibration Start Pos down to zero and then
turn it up until the calibration light appears as a glow at one side of the
image. Then turn the value down a small amount until the light vanishes
again. Setting this control allows the GPS frame start time to be corrected
for the time difference between the camera circuitry requesting the frame
starts and the actual exposure starting.
With the GPS LED on, set this to a value just above the calibration Start
Pos value and then turn up the value until the LED light vanishes again.
Turn the value down a small amount until the light re-appears.
This allows the end of frame time to be adjusted for the time difference
between the camera circuitry requesting the frame to stop and the frame
having finished.
After calibrating the Start and End Pos, don't forget to turn the calibration
LED off again. Also, note that the calibration needs to be repeated after
having changed the camera exposure or the camera colour space.
Image Controls
White Bal (R) [Colour Modes
only]
White Bal (B) [Colour Modes
only]
White Bal (G) [Colour Modes
only]
Thermal Controls
Cooler Power
Target Temperature
Controls the relative intensity of the red channel of a colour
image.
As for White Bal(R) above, but controls blue.
As for White Bal(R) and (B) above, but controls green channel.
Allows the percentage power that the cooler runs at to be set. If
set to Auto, then the cooler will automatically attempt to cool the
sensor to the temperature given by the Target Temperature
control.
Sets the sensor target temperature for use when the cooler power
is set to Auto.
Page 66 of 157
SharpCap 2.9 User Manual
11.2.7 ZWO Camera Controls
SharpCap supports the full range of ZWO cameras, including support for high resolution ASI1600
cameras and cooled cameras.
Drivers and further information can be found at the ZWO website.
Camera Controls
Camera Controls
Turbo USB
Controls how fast the camera will try to push data over the USB bus.
Setting a higher value will try to move data faster and give higher frame
rates, but setting a value too high can cause:
•
•
•
High Speed Mode
Hardware Binning
Dropped frames.
A collapse in frame rate.
Or even no frames at all.
In general, leaving this setting on Auto will work well in most
circumstances, but if there are issues with no frames, stuttering frames or
low frame rates then try adjusting this option.
May improve the frame rate under some circumstances. Changes from
using the 12bit ADC on the camera to using a 10bit ADC. Enabling high
speed mode may increase image noise when the gain is set to a low value.
Only applies when binning is enabled. Calculates binning on the camera
itself rather than in software in the camera driver. Increases gain and
noise and increases frame rate.
Page 67 of 157
SharpCap 2.9 User Manual
Image Controls
Image Controls
White Bal (R)
[Colour Modes only]
White Bal (B)
[Colour Modes only]
Mono Bin [Colour
Cameras only]
Controls the relative intensity of the red channel of a colour image. Along
with White Bal (B) this can be used to correct the white balance of an
image. Note that setting either of the two ZWO white balance controls to
auto sets them both to auto.
As for White Bal(R) above, but controls blue. Note that there is no control
for the green channel, but that isn't needed as the relative strength of the
green channel can be increased or decreased by making the opposite
change to both red and blue.
Only applies when binning is selected. Creates a monochrome binned
image rather than a colour binned image.
Thermal Controls
Thermal Controls
Cooler On/Off
Target Temperature
Cooler Power [Read
only]
Turns the camera cooler on or off. The camera must be connected to 12V
power to allow the cooler to operate.
The temperature the camera will try to achieve if the cooler is turned on.
The current power percentage that the cooler is running at.
Page 68 of 157
SharpCap 2.9 User Manual
Miscellaneous Controls
These control the auto exposure and auto gain
functions of the camera.
Miscellaneous Controls
Auto Exp Max
Auto Exp Max Brightness sets the target level for the maximum brightness
Brightness
point in the histogram in the range 50 (targets a histogram peak at about
the 20% level) to 150 (targets a histogram peak at about the 60% level).
Auto Exp Max Exp
Auto Exp Max Exp is the maximum exposure (in seconds) that can be used
when auto exposure is enabled.
Auto Exp Max Gain
Sets the max allowable gain in the same way.
11.2.8 DirectShow Cameras
Microsoft DirectShow is an architecture for streaming media on the Microsoft Windows platform.
There are a vast number of webcams and frame grabbers on the market. In general, SharpCap
should work with any of them but some cameras/grabbers have buggy drivers which may prevent
them from working correctly with SharpCap. The controls available in SharpCap are determined by
the driver – SharpCap just shows the controls the driver makes available. Sometimes more controls
are available in the Video Capture Pin and Video Capture Filter dialogs provided by the device driver.
Additionally, SharpCap allows the images being captured from a webcam to be processed by
sophisticated features available to dedicated astro cam users – for instance Live Stacking and Polar
Alignment are both usable with images coming from a webcam or frame grabber provided a long
enough exposure can be set to start seeing details and/or stars.
For a DirectShow camera, dark frame subtraction can only be applied in the Live Stack controls, not
in the Camera Control Panel.
11.2.8.1 Webcams
Many budget webcams usually need some adaptation to be used for imaging. This usually involves
removal of lenses, auto-focusers (which includes the infra-red filter) and addition of a webcam 1.25”
adapter and IR cut filter. Furthermore, complex modifications of an electronics nature can be
performed to provide long-exposure (LX) capability and amp-glow removal, although this tends to be
limited to older cameras such as Philips SCP900 and Toucam models.
11.2.8.2 Microsoft LifeCam (webcam)
The Microsoft LifeCam HD is a common web cam which can be modified for astro use – it would
typically be used for lunar/planetary image capture but not deep sky objects. Its capability can be
seen in the Jupiter images at the SharpCap gallery .
Page 69 of 157
SharpCap 2.9 User Manual
These webcams can be found on eBay for around £15 and would need an IR cut filter (around £10 on
eBay). Modification details can be found at http://dslrmodifications.com/lifecam/lifecam1.html,
showing the camera being fitted into a disused or low cost telescope eyepiece.
Original Microsoft LifeCam
Modified and fitted into a 1.25” eyepiece
Showing IR cut filter
Sensor view
When a Microsoft LifeCam is the active camera, additional menu Options appear in SharpCap.
With the Microsoft LifeCam, the useful extra options are:
•
•
Video Capture Filter
Video Capture Pin
There is also the option to
•
Enable LX mode. LX (= Long eXposure) is an on/off toggle.
Page 70 of 157
SharpCap 2.9 User Manual
Warning: Enabling LX mode is only for use with hardware modified cameras having had circuitry
added to control the sensor exposure directly from the PC via a serial or parallel port. Ticking this
box on a camera not having had this modification will not give access to longer exposure options.
Video Capture Filter and Video Capture Pin are options which show setup dialogs created by the
camera’s manufacturer. The Video Capture Filter dialog can also be accessed via the Camera Control
Panel by pressing the ‘Show’ buttons next to the options control.
Video Capture Filter
Video Capture Pin
11.2.9 Frame Grabbers
A frame grabber is an electronic device able to capture frames from an analogue video signal. The
frame grabber is a USB device. The analogue video signal is commonly supplied by a day/night CCTV
style security camera. This type of camera, generically called an astro video camera, is commonly
based on the LN300 style CCTV body, usually with enhanced firmware or electronics which allow for
internal stacking of video frames. Camera output can be to a frame grabber or an analogue screen.
This arrangement is commonly used for live image display and internet video broadcasting of
astronomical objects particularly in outreach type scenarios. This arrangement has proved to give
satisfactory results under heavily light-polluted skies.
A typical video capture device is the EzGrabber from http://www.ezcap.tv/. [Note: there are lots of
clone devices that look the same as the ezcap but may contain completely different hardware and
have different drivers – sometimes these drivers have compatibility problems.]
Well known manufacturers of the astro video type cameras are Revolution Imager and Mallincam.
A typical setup comprising frame grabber and astro video camera is shown below.
Page 71 of 157
SharpCap 2.9 User Manual
Analogue video camera with Bluetooth adapter
for accessing the camera’s internal menu.
Video/power balun (left hand side) used to
connect ethernet cable.
USB2 video frame capture device. Shows in
SharpCap as a USB 2861 device.
From left to right –
video frame grabber, balun, ethernet cable, balun, analogue video camera.
SharpCap will see this USB frame grabber as a USB 2861 (typically 28xx) device. The details of the
camera connected to the frame grabbing device will not be detected by SharpCap. The camera is
controlled by its own internal menu system and is usually accessed via a USB or Bluetooth
connection. This type of camera typically has a maximum resolution of 720 x 576 and will be NTSC
or PAL.
SharpCap view of a frame grabber
Astro video camera internal menu
Page 72 of 157
SharpCap 2.9 User Manual
11.2.10
Modified Webcams
Modified webcams are those which have been electronically modified. Typical modifications are
long-exposure (LX) and amp glow removal. SharpCap still supports LX modified webcams controlled
either by serial or parallel interfaces.
The Philips SPC 900N (LX Mode) is an example of such a camera. Its capability can be seen in the
deep sky, lunar and solar images at the SharpCap gallery .
The Philips webcam shown below was originally an SPC 880. It had a firmware upgrade to SPC 900
and was modified to fit into a telescope. Subsequently the SC1 long-exposure modification (parallel
port) was carried out, details at http://www.astronomiser.co.uk/toucam.htm .
Original Philips SPC 880 webcam
Modified SPC 900 showing parallel port LX mod.
Additional options appear in SharpCap for this type of camera.
With the Philips SPC 900N, the extra options are:
•
•
•
•
Serial LX Configuration
Parallel LX Configuration
Video Capture Filter
Video Capture Pin
Video Capture Filter and Video Capture Pin are options which are better accessed via Camera
Controls.
Page 73 of 157
SharpCap 2.9 User Manual
This camera has the long-exposure modification which is controlled via a parallel port cable. The LX
option gives access to further configuration settings. These are the usual settings but it depends on
how the LX setup is wired and some experimentation may be required.
11.2.11
DirectShow Controls
DirectShow cameras have a fixed set of available controls defined by Microsoft, however not all
cameras will offer all these controls.
Format & area (Video format)
• Colour space
• FPS
• Resolution
• Frame divisor
11.2.12
Camera controls
• Pan
• Tilt
• Roll
• Zoom
• Exposure
• Iris
• Focus
Image controls
• Brightness
• Contrast
• Hue
• Saturation
• Sharpness
• Gamma
• Color Enable
• White Balance
• Backlight Compensation
• Gain
Test Cameras
The Test Cameras are useful to experiment with and understand settings and their effect. Much of
the material in this manual has been derived from the Test Cameras. Hence this document can be
used as a learning aid without having a telescope or camera attached to the PC/laptop or when the
sky is cloudy. The use of a suitable lens (which can be purchased for a few pounds) will allow astro
cameras to be tested without waiting for clear skies.
Test Camera 1 (Deep Sky)
See Common Camera Controls for a description of generic camera/image/display controls. [Note:
some of the common controls currently have no effect, for example gain.]
Page 74 of 157
SharpCap 2.9 User Manual
•
•
•
•
•
•
Image – click the Properties button to load a PNG file stored in the SampleFiles folder. Other
user created PNG, JPG or FITS files can be stored here for access via the test camera.
Random Rotation – applies a random small rotation to each frame shown in the capture
display area. On/Off, default = Off.
Random Offset – applies a random offset effect to the image shown in the capture display
area. On/Off, default = Off.
Random Seeing – applies a random seeing effect to the image shown in the capture display
area. The seeing effect is a blurring of the image. On/Off, default = Off.
Random Noise(On/Off) – applies a random noise effect to the image shown in the capture
display area. Default = 10, range 0..50.
Add Dark Noise – will, by default, apply the file SampleFiles\1280x960x32RGB_dark.png to
the image shown in the capture image. The image used for dark noise can be changed by
pressing Properties – the image must be the same size as the main image.
Test Camera 2 (High Speed)
See Common Camera Controls for a description of generic camera/image/display controls. [Note:
some of the common controls currently have no effect i.e. gain, exposure, gamma.]
•
•
•
•
Focus Offset – simulate focuser movement and can be used in Focus Score > Graph. Default
= 0, range -10..+10.
Random Offset – applies a random offset effect to the image shown in the capture display
area. On/Off, default = Off.
Random Seeing – applies a random seeing effect to the image shown in the capture display
area. The seeing effect is a blurring of the image. On/Off, default = Off.
Random Noise – applies a random noise effect to the image shown in the capture display
area. Default = 10, range 0..50.
Page 75 of 157
SharpCap 2.9 User Manual
12 The Histogram
The image histogram acts as a graphical representation of the tonal distribution in a digital image. It
plots the number of pixels for each tonal value. The histogram will quickly highlight problems with
an image including under exposure, over exposure or colour balance issues and is used to help
capture the highest quality data possible.
The histogram can be shown by clicking the Image Histogram icon in the Tool Bar:
which will display the Image Histogram in the Work Area of the Main Screen, as shown below.
Clicking the FX Selection Area icon in the Tool Bar shows a red rectangle on the image which can be
dragged and re-sized. While this selection area rectangle is enabled, the histogram is only calculated
for the parts of the image within the rectangle. This allows for more detailed scrutiny of a restricted
region of the image and of how the histogram in the region appears.
Page 76 of 157
SharpCap 2.9 User Manual
Notice the two histograms above are different but no camera settings have been changed.
12.1 The Histogram in Detail
Auto Hide – at the top right, the ‘pin’ icon can be used to auto hide the histogram when the mouse is
moved away from it. Moving the mouse back over the collapsed histogram tab will re-show it.
Logarithmic/linear selection – the checkbox will switch between a logarithmic display and a linear
display.
Horizontal axis – the % of maximum pixel brightness (in 8 bit modes the pixel brightness is 0 to 255,
in 16 bit modes 0 to 65535). This is scaled as 0 – 100 and caters for 8-bit, 12-bit, 14-bit and 16-bit
cameras in a uniform presentation.
Vertical axis – the number of pixels at that brightness.
Page 77 of 157
SharpCap 2.9 User Manual
The Histogram Lines – The four lines on the histogram graph showing the brightness distribution of
each of the three primary colour channels (Red, Green and Blue) and the distribution of the total
brightness of each pixel (often referred to as Luminance).
Horizontal Colour Bars – these bars below the horizontal axis represent the ranges of the Luminance,
Red, Green and Blue channels (commonly referred to as LRGB).
This histogram below conveys the following information:
•
•
Approximately 400k pixels have 3% of maximum pixel brightness. This is the histogram
peak.
Approximately 15 pixels have 100% of maximum pixel brightness”, that is, are saturated in
this case. This is a very small number of pixels compared to the total number in the image,
so the clipping at the right-hand side is of little significance.
Note when using a Mono colour space, there is only a single white horizontal bar (Luminance) and
single line on the graph.
Page 78 of 157
SharpCap 2.9 User Manual
12.2 Understanding the Histogram Axes
The diagram below defines the units of the horizontal and vertical axes.
Note SharpCap shows the horizontal scale as a %, giving a uniform method of labelling to cover 8, 12,
14 and 16-bit cameras.
The horizontal scales can be found on the internet using a representation of the bit depth capability
of the camera. The table indicates alternate horizontal scales that may be encountered, the
numbers being derived as 2n-1, where n = bit depth of camera.
Camera bit depth
8
12
14
16
Histogram horizontal scale
0..255
0..4095
0..16383
0..65535
Page 79 of 157
SharpCap 2.9 User Manual
12.3 Linear and Logarithmic Scales
By deselecting or selecting the Logarithmic checkbox at the top right, the shape of the SharpCap
histogram can be changed.
Vertical scale is linear, checkbox not selected
Vertical scale is logarithmic, checkbox selected
In the graphics above, notice the vertical scales are different. The following is a description of the
difference between Linear and Logarithmic scales.
Note: ~ means approximately in the calculations. The slight inaccuracies are due to rounding errors
when scaling to fit the screen.
Linear Scale
•
•
•
•
•
•
is unchecked in the Image Histogram.
The numbers are uniform.
The tick marks are equally spaced.
The tick marks have uniform differences between their values.
The values are 0, 37k (1*37), 75k (~2*37), 113k (~3*37k), 150k
(~4*37k), 188k (~5*37k).
The increment from one tick mark to the next is ~37k (37000), that is
37k is added to each value to get the next value.
If the graph is twice as high in one place (say at 50% brightness) as
another (say 25% brightness), meaning there are twice as many pixels
with 50% brightness as with 25% brightness.
Page 80 of 157
SharpCap 2.9 User Manual
Logarithmic Scale
•
•
•
•
•
•
•
is checked in the Image Histogram.
The numbers are non-uniform.
The tick marks are equally spaced.
The tick marks do not have uniform differences when moving from
one value to the next – instead they are multiplied by some amount.
For instance, the values are 13, 180 (~13*13), 2400 (~13*13*13) and
so on.
Those who can remember basic algebra, will recognise 130, 131, 132,
133 and so on.
The vertical scale increases the height of areas where there are small
values and reduces the height where there are large values.
Becomes easier to see those parts of the graph with a much-reduced
number of pixels at each level.
Logarithmic scales help to get all the data on the chart so the values
are readable – they supress the high values and enhance the low
values.
After reading the above, the question is “Should a Logarithmic scale or a Linear scale be chosen
when using the Image Histogram?”
The answer is “think about the type of object being imaged and use whichever obtains the best
images” but, bear in mind the following:
•
•
Linear makes most sense when the area the histogram is being applied to is roughly uniform
in brightness, for instance:
o A lunar or solar image when the frame is filled.
o A planetary image when the ROI is used to select a region inside the planetary disk.
Logarithmic makes sense when there are distinct different regions inside the histogram area,
for instance:
o A deep sky full frame containing a small area of nebulosity.
If the deep sky was looked at with a linear histogram, the peaks from the nebulosity and
stars would be swamped by the vast black level peak and therefore invisible. However, the
logarithmic scale gets around this.
The following two examples both use a logarithmic scale but depending on the type of object being
imaged (deep sky or large disk) the desired histogram shape is totally different.
Page 81 of 157
SharpCap 2.9 User Manual
Large Disk
Deep Sky
12.4 Using the Histogram to Improve Image Quality
The shape of a ‘good’ Histogram can vary depending on:
•
•
A logarithmic or linear vertical scale being selected.
The object being viewed:
o Deep Sky.
o Solar/Lunar/Planetary.
o Solar/Lunar/Planetary when ROI (Region of Interest) is used to select an area inside
the disk.
Guidelines for ‘good’ histogram shapes for linear/logarithmic vertical scales and object types are
summarised below. Following these guidelines will help ensure images are correctly exposed.
Page 82 of 157
SharpCap 2.9 User Manual
Deep sky - linear
Deep sky - logarithmic
Solar/lunar/planetary – linear
Solar/lunar/planetary - logarithmic
Solar/lunar/planetary with ROI or when target
is filling frame (i.e. no black background) –
linear
Solar/lunar/planetary with ROI - logarithmic
It is helpful to consider the following information to understand why these shapes of histogram are
associated with the given types of image:
•
•
•
Deep sky histograms have a peak at low intensity levels due to the dark background and
typical low brightness of any nebulosity.
Solar/lunar/planetary histograms usually have a peak near the black level due to the dark
background and another peak for the (relatively) large and bright image.
Solar and Lunar histograms where an ROI is used or the sun/moon fill the entire frame will
not have a peak near the black level as there is no black background.
The following two diagrams show the type of problems (plus suggested fixes) encountered with a
histogram.
Under-exposed image
When the histogram looks like this (shifted too
far left), the image is said to be under-exposed
or black level clipped. This will result in an
image with a grainy background. The grainy
background is difficult to remove with postprocessing software. Faint detail will be hard to
bring out. To fix, expose the image for longer
(preferred) and/or increase gain and/or
increase brightness or offset.
Page 83 of 157
SharpCap 2.9 User Manual
When the histogram looks like this (shifted too
far right), the image is said to be over-exposed.
Pixels in the image become saturated, resulting
in detail being lost. To fix, expose the image
less (preferred) and/or reduce gain.
Over-exposed image
12.5 Worked Examples
The following two examples use these guidelines (not rules) for a ‘reasonable’ histogram for a deep
sky object with the vertical axis set to use a logarithmic scale:
•
•
•
•
•
•
•
Horizontal LRGB bars not touching left axis (otherwise black clipped).
Horizontal LRGB bars not touching right axis (otherwise white saturated).
Red and blue horizontal bars approximately level at each end (colour balance).
LRGB histograms very close together in the graph.
Histogram peak at around 20% on horizontal axis. The peak can move depending on light
pollution.
Sharp gradient at left of peak.
Gentle gradient to right of peak.
12.5.1 A Monochrome Deep Sky Example
The example below documents the preparation to image M42. The equipment used was:
•
•
•
•
•
Celestron C8 SCT.
Celestron CG5 Equatorial Mount.
Altair Astro GPCAM MONO V1 set to MONO8 colour space.
A 0.5x focal reducer and Astronomik CLS filter.
Imaging laptop was a Lenovo X61 ThinkPad, with 1.8GHz Core 2 Duo CPU, 4Gb RAM, 120Gb
SSD & Windows 10 Pro 32-bit.
Page 84 of 157
SharpCap 2.9 User Manual
The M42 object has a wide range of brightness. Rather than try to set exposure and gain for the
whole image, the FX Area Selection tool was used to set the histogram for a restricted area,
effectively excluding the bright core of M42 from the calculations. This choice led to the core being
over exposed but gave a chance of capturing the nebulosity – a trade-off.
Checking against the guidelines listed above for a deep sky object with the vertical axis set to use a
logarithmic scale:
Guideline
Horizontal LRGB bars not touching left axis
(otherwise black clipped).
Horizontal LRGB bars not touching right axis
(otherwise white saturated).
Red and blue horizontal bars approximately
level at each end (colour balance).
LRGB histograms very close together in the
graph.
Histogram peak at around 20% on horizontal
axis.
Sharp gradient at left of peak.
Gentle gradient to right of peak.
Whether satisfied
Yes, mono therefore no RGB.
Touching, but looking at the log
scale, ~80 pixels saturated.
Not applicable, as mono.
Not applicable, as mono.
At 10% but shape is good.
Yes.
Yes.
The stack was cleared and stacking restarted, the histogram was still reasonable, nebulosity was
starting to build after 1 x 30s frame.
Page 85 of 157
SharpCap 2.9 User Manual
At each stage, most attention was paid to the histogram in the Work Area.
Here is a copy of the FITS capture file loaded into FITS Liberator – with no post-processing. The
histogram had kept ‘reasonable’ shape suggesting worthwhile data was being captured for
subsequent processing.
Page 86 of 157
SharpCap 2.9 User Manual
12.5.2 A Colour Deep Sky Example
This capture was taken using an AVS DSO-1 analogue video camera with USB2 video capture device
(frame grabber). The video grabber is classed as a DirectShow device, no camera controls are
exposed in SharpCap, so adjustments are made using the camera’s internal menu.
Checking against the guidelines listed above:
Guideline
Horizontal LRGB bars not touching left axis (otherwise black clipped).
Horizontal LRGB bars not touching right axis (otherwise white saturated).
Red and blue horizontal bars approximately level at each end (colour balance).
LRGB histograms very close together in the graph.
Histogram peak at around 20% on horizontal axis.
Sharp gradient at left of peak.
Gentle gradient to right of peak.
Whether
satisfied
Yes.
Yes.
Reasonable.
Yes.
Yes.
Yes.
Yes.
The four Trapezium stars at the core of M42 can be seen. Improvements here would be to try to
extend the histogram more to the right, by adjusting exposure, gain and brightness.
The resultant Save as Viewed PNG file when the Live Stack count was 293 is shown below (Save as
Viewed = no post-processing). The core was blown out but some nebulosity was captured.
AVS DSO-1 camera settings
• AGC = 36
• Colour = Red 63, Blue 101
• INTG = X8
• Brightness = 60
• Gamma = 0.3
• INTMUL = 5
Page 87 of 157
SharpCap 2.9 User Manual
13 Live Stacking
Live stacking is a feature that enables the capture of deep sky images within SharpCap without the
traditional requirements of a high accuracy, guided, equatorial mount and long sub-frame
exposures. The capture of a larger number of shorter exposures and software correction within
SharpCap for any drift or rotation of the field of view between frames makes deep sky
astrophotography accessible to a much wider audience at much lower cost.
The traditional requirements of long exposures and accurately guided mounts arise from traditional
CCD cameras used for deep sky astrophotography have a high-level of read noise. If there is a high
read noise every time that a frame is captured, long exposures are required to allow faint deep sky
objects to be seen above the read noise level. Long exposures mean that an equatorial mount which
tracks accurately and is typically auto-guided is required.
This all changes when modern low noise CMOS cameras are used instead of CCD cameras. The low
level of read noise means that faint objects can be detected in far shorter exposures (and can be
enhanced by stacking many short exposures – something that would not be possible without low
read noise). If exposures are short enough (often 30s or less), mount accuracy is less important as
the amount of drift during a 30s exposure is far smaller than the drift during a 300s exposure. Away
from the zenith, field rotation due to the use of an ALT/AZ mount is also not usually going to be
significant during a single 30s exposure. SharpCap corrects for any gradual drift or rotation between
successive frames by tracking the movement of the brightest stars in the image. As the number of
frames captured increases the noise level visible initially visible in the stacked image will reduce
giving astounding deep sky images with the minimum of fuss.
Because of the simple satisfaction of watching deep sky images appear in real time without the need
to use a separate stacking program, Live Stacking is particularly well suited to outreach uses.
Live Stacking is started by choosing the ‘Live Stack’ option from the Tools menu or by selecting the
Live Stack toolbar button.
Once selected, Live Stacking will immediately begin capturing, aligning and stacking frames. A
minimum of 3 stars must be detected in each frame for alignment to be possible (see the following
sections for further details on alignment and how to customize star detection). It is possible to save
the stacked image at any point using the Save button that appears in the Live Stack work area – the
Save can be repeated as required – for instance after 50 frames and again after 100 frames and so
on.
13.1 The Live Stacking User Interface
The UI to control Live Stacking appears in the work area below the camera image, and is divided into
an always visible left panel and a series of tabs to the right.
The left panel controls and reports on the most important aspects of the stacking process and is
always visible during Live Stack. The right panel has six tabs to allow the monitoring and control of
the details of the Live Stack process.
Page 88 of 157
SharpCap 2.9 User Manual
13.1.1 Left Panel
Overview Group
• Frames Stacked – the current number of frames on the stack.
• Frames Ignored – the number of frames ignored (not stacked). This can happen because of
alignment problems, SharpCap not seeing enough stars, frame failing to achieve a focus
score criteria or other reasons.
• Total Exposure – the length of time the current stack has been running. Some cameras
cannot report their exposure value to SharpCap (for instance DirectShow Frame Grabbers).
In those cases, SharpCap estimates the exposure based on the time between subsequent
frames.
Controls Group
• Align Frames – turn alignment and de-rotation on/off (default on). See Alignment tab on
right panel for more details.
• Enable FWHM Filter – enable/disable filtering of each frame by the average FWHM (focus
quality) value. High FWHM value frames are discarded as indicating poor
focus/seeing/transparency/cloud. See Filter tab.
• Subtract a Dark Frame [only available for DirectShow cameras – other cameras can subtract
a dark frame in the camera control panel].
• AutoSave – enable/disable saving the stack automatically when the clear button is pressed
or another action causes the stack to be reset.
• Save Individual Frames – when enabled save each frame as a separate file (FITS/PNG). Note,
all frames are saved, not just ones passing the filtering criteria. The individual frames will be
found in a folder like YYYY-MM-DD\Capture\HH_MM_SS\rawframes.
In the Show group, there is a choice to display either the stacked image or the individual frames
being acquired from the camera.
• Stack (show the stack so far – the default)
• Individual Frames (show the individual frames being captured by the camera)
Page 89 of 157
SharpCap 2.9 User Manual
The Clear button will reset the stack to start from scratch. Note, other actions can cause the stack to
be reset; for instance, changing camera, resolution, colour space. Changes to exposure, gain,
brightness or applying a dark/flat will not cause the stack to be reset.
The Save button has 3 sub options:
•
•
•
Save as 16 Bit Stack will rescale the stacked data linearly between the 0 and the maximum
pixel value into the range 0 to 65535 and save this as a 16 bit FITS file. The 16-bit FITS option
is the default as it gives a high bit depth image with the full range of the image used (i.e.
brightest pixel is 65535).
Save as Raw (32-bit) Stack will save the full 32-bit stack data without any scaling as a 32-bit
FITS file. The maximum value in it will depend on the number of frames stacked, meaning
more adjustments will be needed when viewing (without further adjustment this FITS file
will probably appear black when opened into a FITS viewing application).
Save as Viewed will save the image as seen on screen (i.e. after histogram adjustments have
been applied) as an 8 or 16 bit PNG file (depending on bit depth of camera being used).
The Pause/Resume button will temporarily stop or resume stacking. Stacking will automatically be
paused if the Live Stack window is closed or if the user switches to another tool such as Histogram.
Switching back to Live Stack will allow stacking to be resumed in these circumstances if another
action would cause the stack to reset has not been carried out (for instance changing resolution or
colour space).
13.1.2 Status Tab
The Status tab shows some more detailed information about the stacking process and the stack so
far. Of interest is the stacking time, which is the amount of time taken to process the alignment and
stacking calculations needed for each frame. If this time is longer than the exposure length, frames
will be dropped from the stack (due to the previous frame still being stacked when the next frame
arrives). The right-hand information panel shows warning or error messages if stacking errors are
occurring.
Page 90 of 157
SharpCap 2.9 User Manual
13.1.3 Histogram Tab
The Histogram tab shows not only the image histogram but allows White Level, Black Level, and
Gamma to be adjusted to pull out more faint detail in a stacked image (The Whirlpool Galaxy is a
classic example of when to use the sliders). The Live Stack histogram shows the data for the stack so
far (not for the individual frames, even when show individual frames is checked).
• Tweaks to the Black Level, White Level and Gamma affect how the image is shown on screen
and how it is saved if choosing Save as Viewed.
• The changes do not affect the actual values in the stack or the result if Saving As 16 or 32 bit
stacks.
• Additionally, the Display Controls on the right, in the Camera Control Panel, affect only how
the image is viewed on screen and do not affect any saved data whatsoever. The Display
Controls Gamma/Brightness/Contrast are applied only to the image being drawn on the
screen.
Adjust White Level
• The white level applies to the horizontal axis of the histogram, so left is 0% and right is
100%. It is not usually necessary to adjust this control.
Adjust Black Level
• The black level applies to the horizontal axis of the histogram, so left is 0% and right is 100%.
• Turn up the Black Level slightly (move slider to right) to suppress sky glow/chip noise and
give a dark background to an image. Turning the black level up too far can give the image an
unnatural look.
Gamma
• Turn down the Gamma (move slider downwards) to boost faint data. (In SharpCap version
2.10 there are extra controls for smoothing the transition at the black point and for fine
adjustment of the black level). The range of the gamma is from 0.1 (bottom) to 2.0 (top).
Transfer Curve
• The Red transfer curve shows how the levels between the black and white points are going
to be displayed on screen. The shape of this line is determined by the settings for the black
point, white point and gamma controls, and the line acts in a way similar to the ‘Curves’
adjustment found in many image processing applications. For this line the vertical axis of
the graph is the display brightness from black (bottom) to white (top). The brightness of a
pixel in the viewed image is calculated by taking its horizontal position of the pixel on the
histogram, moving up to the red transfer curve line and taking the vertical position of the
Page 91 of 157
SharpCap 2.9 User Manual
line at that point as the displayed brightness for that pixel.
Reset Adjustments
• Restores the controls back to their defaults (buggy in v2.9, doesn't reset some controls).
13.1.4 Alignment Tab
The Alignment tab controls the alignment process which, along with the FWHM filter, depends on
the detection of stars in each image. SharpCap can only align images in which it can detect stars (do
not use Live Stack for planetary or lunar images).
•
A minimum of 3 stars is required for Live Stack with alignment to work. However, for
reliability and good alignment a star count of 10-15 or more is to be preferred.
Alignment Group
• Align Frames – enable or disable the alignment of frames. The first frame in any stack
becomes the reference frame – all other frames are aligned with that frame when alignment
is enabled. SharpCap uses the stars it detected in the first frame to align all subsequent
frames with the stack. Stars in the stack are re-detected if any of the star detection
parameters are changed. The absolute minimum requirement is 3 stars detected, although
having 3 stars is no guarantee of alignment working if too close together or close to being in
a straight line for instance. Ideally, aim for 10-20 or more stars detected with a good
distribution across the frame.
• Allow De-rotation – check box cannot be changed and will be removed in a future version.
• Align using – to select number of stars. It can be 10, 15, 20 or 25 stars. Using a larger
number of stars may slow down the stacking process, but may give better alignment results.
Only increase this value if detecting plenty of stars but still having difficulty aligning.
Star Detection Group
• Reduce Noise – when enabled applies a Gaussian blur to help SharpCap to ignore low level
noise and hot pixels. Selecting Reduce Noise is recommended.
• Black Level Threshold – anything under this level is treated as black and can help to ignore
low level noise. The default is 50, the range 1..254 in steps of 2 by pressing the up/down
arrows. Any value required (in the range) can be typed directly into the box.
• Digital Gain – can be used to apply a gain during the star detection process if stars are faint
and are not being detected. Values can be Off, 2x, 4x, 8x. Enabling this may help if
SharpCap is not detecting enough stars.
Page 92 of 157
SharpCap 2.9 User Manual
•
•
•
Minimum star width – increase this to help stop hot pixels being detected as stars. The
default is 2, range 2..32 in steps of 2 by pressing the up/down arrows. Any value required (in
the range) can be typed directly into the box.
Maximum star width – reduce this to limit detection of very bright bloated stars. The default
is 16, range 4..32 in steps of 2 by pressing the up/down arrows. Any value required (in the
range) can be typed directly into the box.
Highlight Detected Stars – checking this will put boxes around the detected stars – yellow
stars are used for alignment, red are not used for alignment. This can be very helpful to
determine and understand the causes of problems with star detection and alignment.
Status Group
• Shows various data including offset of the frame from the stack, rotation, calculation time
and number of stars detected. Note, if the stacking time (the time taken to calculate
alignment and process the stacking of each frame) exceeds the exposure time, frames will
be ignored by the live stacking as new frames will arrive while the previous frame is still
being processed.
Page 93 of 157
SharpCap 2.9 User Manual
13.1.5 Filter Tab
The filter allows poor-quality frames (poor atmospheric conditions or clouds) to be excluded from
the stack. Quality is currently judged only by the FWHM (full-width-half-maximum) estimate of the
quality of focus in the frame.
•
•
•
Filter on FWHM – check to enable FWHM (focus score) filtering.
Maximum FWHM – use the slider to specify a maximum FWHM value for frames to be used.
It shows a history of recent frames. Used frames are green, frames discarded by filtering are
red.
Filtering does not apply to the first frame in any stack
13.1.6 Darks Tab
A dark can be applied in Live Stacking when using a webcam/frame grabber (DirectShow camera).
For other cameras, darks must be applied via the main camera controls.
When darks are being applied, it is possible for the dark frame to have higher pixel values at some
points than the light frame (due to random noise in dark areas). This leads to negative pixel values in
the dark subtracted frame, which SharpCap preserves and adds to the stack. In general, these will
cancel out with positive (+ve) pixel values at the same point in other frames, leading to overall better
images with less noise than if the negative (-ve) values were discarded.
The requirement to allow for negative (-ve) pixel values means 16-bit pixel values are downscaled to
15 bits (0..65535 range dropped to 0..32767) when live stacking. As none of the cameras currently
supported by SharpCap produce a true 16-bit output (most are 10, 12, 14 bit scaled up to a 16-bit
range), there is no loss of quality due to this.
Page 94 of 157
SharpCap 2.9 User Manual
13.1.7 Log Tab
Shows some log information of Live Stacking in more detail than is saved in the main SharpCap log.
If something is not working, this is the place to look.
13.2 Live Stack Reference
In the background, SharpCap maintains a 32-bit integer value for each pixel of the stack with the
value from each frame being added to the pixel value.
•
•
For a 16-bit camera it is possible to stack up to 32768 (215) frames before running out of
values in the stack.
For an 8-bit camera it is possible to stack up to 16 million frames (224) before running out of
values in the stack.
All files saved during a stack will be saved in a single folder (raw frames and processed stack images
saved in subfolders). This helps keep the saves from the stack together. The folder is named after
normal file naming rules based on the time stacking was started and the name of the target object
selected.
If the name of the target in the toolbar is changed during Live Stacking, SharpCap will rename the
output folder.
13.3 Using Live Stacking
A useful video demonstration of using the Live Stack function in SharpCap can be found, courtesy of
Charles Copeland, at https://www.youtube.com/watch?v=zIlJHyVWei4 .
Although the video shows SharpCap 2.7, it is still valid for SharpCap 2.9 and beyond. This is a good
demonstration of what can be achieved with video stacking software using a NexStar 6SE telescope,
analogue video camera and 0.5x focal reducer. Be aware of the comment “if using v2.9 be sure to
set Digital Gain to 2X in the Alignment tab” on the web page, below the video. This may be helpful if
Page 95 of 157
SharpCap 2.9 User Manual
it is difficult to detect enough stars, however turning on the Digital Gain when it is not required will
reduce alignment accuracy slightly.
The video is worth watching again and again ……
13.4 Sample Live Stack Session
The example below documents the preparation and process to image M42, the Orion Nebula. The
equipment used:
•
•
•
•
•
Celestron C8 SCT.
Celestron CG5 Equatorial Mount.
Altair Astro GPCAM MONO V1 set to MONO8 colour space.
A 0.5x focal reducer and Astronomik CLS filter.
Imaging laptop was a Lenovo X61 ThinkPad, with 1.8GHz Core 2 Duo CPU, 4Gb RAM, 120Gb
SSD & Windows 10 Pro 32-bit.
Below is the workflow for the image capture session.
1. Use the focus score tool FWHM Measurement to achieve good focus – see Focusing.
2. Adjust the camera controls (not the Display Controls), to get a good histogram shape
without guessing – see The Histogram.
3. Check against the guidelines for a deep sky histogram (with vertical log scale).
4. Switch to Live Stack – the histogram shown here has a reasonable shape for a deep sky
object.
Page 96 of 157
SharpCap 2.9 User Manual
5. Check to see if the Frames Stacked count is incrementing – if it is, all is well. If not, it is likely
not enough stars are being detected to allow alignment. In this case go to the Alignment tab
and select Digital Gain 2x and Reduce Noise (these are the adjustments most likely to fix the
problem of too few stars detected).
6. From the Tool Bar, create a suitable Target (or Object) name.
Page 97 of 157
SharpCap 2.9 User Manual
A new name can be typed here to represent the current object of interest – such as M42 or
Orion Nebula.
Subsequent captures would be saved in a sub-folder called M42 (or Orion Nebula) under the
default capture folder. Objects added here will not persist across SharpCap restarts. To
become permanent, the object must be added via File > SharpCap Settings > General tab.
7. Clear the stack with the Clear button and restart the stack.
8. When several frames have been stacked, do a Save as Viewed using the Save button
dropdown list.
Page 98 of 157
SharpCap 2.9 User Manual
The resulting PNG file cane be viewed to ensure reasonable data is being captured.
9. Use Save as 16 Bit Stack to create a FITS file. This is a copy of the FITS capture file loaded
into FITS Liberator – no post-processing. The histogram has kept ‘reasonable’ shape
suggesting worthwhile data is being captured for subsequent processing.
10. This is the final image from the stack (no post-processing).
Page 99 of 157
SharpCap 2.9 User Manual
This is how the image progressed as the Live Stack was building.
Stack = 1 (1 x 30s exposure)
Stack = 3 (3 x 30s exposure)
Stack = 10 (10 x 30s exposure)
Image building as Live Stack Frames Stacked count increases
Changing the black level, white level and gamma affect how the image is shown on screen and how
it is saved if choosing Save as Viewed. These actions do not affect the actual values in the stack or
the result if saving as 16 or 32 bit stacks. Additionally, the Display Controls on the right in the
Camera Control Panel can also be used to adjust how the image is displayed on screen. Changes to
the Display controls do not affect any saved data whatsoever – the adjustments specified by the
display gamma, brightness and contrast controls are applied only to the image being drawn on the
screen.
13.4.1 Trouble Shooting Live Stack
The following are common problems:
•
•
SharpCap will report less than 3 stars are visible (3 stars minimum is required to stack
frames) even though there appears to be 3 stars visible in the display.
The Frames Ignored count is increasing (see left-hand side of graphic below).
To find out what is happening, enable the checkbox Highlight Detected Stars. Stars which SharpCap
is using (can see) are surrounded by yellow boxes. In the example below, the problem is poor focus
(deliberate, to force the scenario) and frames are being ignored.
Page 100 of 157
SharpCap 2.9 User Manual
If none are highlighted, consider the following:
•
•
•
Check/Uncheck Reduce Noise.
Try different settings for Digital Gain, including Off.
Investigate the shape of the histogram. Check the black level and minimum/maximum star
widths are reasonable – faint stars will not be found with a 50% black level for instance.
13.4.2 Stretching the Live Stack Image
Stretching an image is a technique, using image level adjustment, which is useful for bringing out
further nebulosity in a deep sky image.
Histogram adjustment can be used to stretch the image during a SharpCap Live Stack capture. The
black point can be set and the gamma adjusted using the appropriate sliders.
Adjustments for the graphic above are:
Page 101 of 157
SharpCap 2.9 User Manual
•
•
•
Move the Black Level slider to the point where the histogram first rises from zero – moved to
the right here.
Usually the White Level slider will not need any adjustment.
Adjust the Gamma slider to personal preference for how bright the nebulosity areas should
be – moved downwards here.
In this example, the red line has been adjusted from straight to curved (stretched) by moving the
gamma slider downwards from its default central position. This action will pull out fainter detail.
•
•
•
The Black Level slider is a % scale.
The White Level slider is a % scale.
Gamma is just a number not a percentage. Neutral gamma is 1 (middle of the vertical bar),
which gives a straight line as the transfer curve (the red line). Correctly interpreted, gamma
of less than 1 will boost the shadows and mid tones, gamma greater than 1 will lower the
mid tones and highlights. [Note: some applications and cameras treat gamma the opposite
way around – increasing gamma boosts the shadows.] The image can also be stretched after
saving using image processing tools.
•
A useful tutorial for applying a stretch function using FITS Liberator can be found at
https://www.aao.gov.au/files/NGC6751_Image_Tutorial_GIMP.pdf . The document also
includes further image manipulation techniques using the open source image processing
application GIMP.
Nebulosity is another program capable of post processing FITS files.
•
Page 102 of 157
SharpCap 2.9 User Manual
14 Focusing
SharpCap has a several options to help acquire focus on targets (possibly one of the most
challenging aspects of astrophotography). The tools are particularly powerful if an ASCOM focuser is
configured in SharpCap (An ASCOM focuser is a device which uses a stepper motor or DC motor to
move the telescope focuser and can be controlled from a computer via a USB cable).
14.1 Introduction
There are six Focus Score tools, the appropriate one must be chosen for the target. Each tool
attempts to measure the quality of focus of the image (the different tools measure the quality of
focus by different methods) and displays the measurement in the work area as both figures and a
graph. The graph may look something like this:
Green bars always indicate better focus while red bars always indicate poorer focus. The most
recent measurements are shown at the right-hand side of the graph with older measurements to the
left. Note, for some tools the best focus is associated with low scores (short bars in the graph), while
for others it is associated with high scores (tall bars in the graph).
It is possible to just select one of the focus tools and adjust the focuser until obtaining the best score
such that the score can no longer be improved by moving the focuser in either direction, but better
results can be obtained with a full understanding of how the process works and the adjustments
available.
Don't try to use the focus tools if the image is a long way out of focus. The tools are to be used to go
from being close to focus to perfectly in focus. If focus is a long way out and there are problems
getting anywhere near focus, try one of the following:
•
•
•
Focus on a terrestrial object at least 200m away in daylight (the further the better), which
will get close to the focus point for astronomical objects.
Use the moon, if it is visible, as it is easy to find and bright. This helps because it can be hard
to find any objects when the telescope is a long way out of focus. However, the moon is
bright enough to be hard to miss even when the focus is very bad.
With high gain and exposure of 2s or so, aim at a bright star or planet. Increase the
brightness of the displayed image by one of the following:
o Selecting 'Image Boost' from the FX dropdown.
o Selecting 'Image Boost More' from the FX dropdown.
o Reducing the 'Display Gamma' control to a smaller value.
If the bright object is either in or near the field of view, all or part of a bright donut
(reflector/SCT) or bright disk (refractor) of light will be seen – this is the very out-of-focus
view of the object, made visible by the high gain and brightness boost. Adjust the focuser of
the telescope to make the disk/donut smaller, which will bring the telescope nearer to
correct focus.
Page 103 of 157
SharpCap 2.9 User Manual
14.2 The Focusing Tools
The six available focusing tools can all be found under the Calculate Focus Score icon from the Tool
Bar. Select the desired tool to begin measuring focus.
14.3 Which Focus Tool Should Be Used?
For a single-star (or sparse) field use either FWHM or Bahtinov Mask.
For a multi-star field use Multi-Star FWHM.
For planetary or surface targets, there are three tools to choose from:
•
•
•
Contrast (Edge) Detection
Contrast (Brightness Range) Detection
Fourier Detail Detection
When trying to focus a planetary or surface target consider the following:
•
•
The different focus score algorithms are attempts to find a better balance between two
opposing factors – sensitivity to being in good focus and insensitivity to noise.
There are trade-offs involved in the various approaches. Which to use is going to be a
matter of trial and error and/or personal preference. The Contrast (Edge) Detection tool is
(probably) a good starting point in most circumstances.
In more detail, the focus tools available are:
Tool
Contrast (Edge)
Detection
Contrast
(Brightness Range)
Detection
FWHM
Measurement
Description
Suitable for planetary or surface targets.
Measures the total amount of contrast in the
image - better focus gives more contrast
which gives higher scores.
Suitable for planetary or surface targets
(especially high noise). Measures the range
between the brightest and dimmest parts of
the image - better focus should give higher
scores.
Suitable for stars or other point sources.
Measures the width (FWHM) of a sole star –
which must be selected using the selection
area tool. Better focus gives narrower stars
and a lower FWHM score
Page 104 of 157
Best Focus
Tall green bars (high values)
are best. Red is worst.
Tall green bars (high values)
are best. Red is worst.
Short green bars (low
values) are best. Red is
worst.
SharpCap 2.9 User Manual
Multi-Star FWHM
Measurement
Fourier Detail
Detection
Bahtinov Mask
Suitable for stars and point sources.
Measures the FWM of all suitable stars in the
frame, giving an average score. Once again,
lower scores mean better focus.
Suitable for planetary or surface targets.
Measures focus by examining amount of
detail in small scales in the image as
determined by a Fourier Transform. Good
focus leads to higher scores. May be less
sensitive to noise than contrast detection
options.
Suitable for stars or other point sources.
Requires a Bahtinov mask to be placed over
the aperture of the scope and the area
around the star and lines to be selected
using the selection tool. Best focus is
achieved when all three lines intersect at the
same point which gives scores (positive or
negative) closest to zero.
Short green bars (low
values) are best. Red is
worst.
Tall green bars (high values)
are best. Red is worst.
Short green bars (low
values) are best – values can
be positive, negative or
zero. Zero equals perfect
focus. Red is worst.
Notes
1. Which is the best focusing method for planets and surfaces? All three see noise as detail to
some extent so picking the right one is a case of trial and error and personal preference.
2. A Bahtinov mask of suitable diameter must be placed over the end of the telescope to use
the Bahtinov Focus Score tool. Negative values are possible, values nearest zero are best, so
-0.1 and 0.1 are equally good, 0.0 is perfect and +3.9 and -3.9 are equally bad.
3. Remember – tall green bars for Planets and Surfaces, short green bars for Stars.
4. Multi-Star FWHM is usually better than single-star because it takes 10s or 100s of FWHM
measurements and averages them, so there should be less noise and less systematic error in
the reading.
14.4 Focusing Procedure
The table details the various steps to be followed to achieve good focus of the telescope.
Telescope (no ASCOM focuser)
Telescope (with ASCOM focuser)
Preparation Phase
• Initial visual focus with telescope against a distant object.
Setup Phase
• Check target not over exposed using Image Histogram tool.
• Select appropriate Calculate Focus Score tool – adjust black level, target detection
parameters, ROI box – to obtain best focus score.
• Reset the graph to wipe the score history.
Focusing Phase
Focusing Phase
Page 105 of 157
SharpCap 2.9 User Manual
•
Adjust telescope focuser manually, watch
focus scores. Stop when best score
obtained.
Telescope now in focus.
•
•
•
•
Adjust telescope focuser using the Focuser
controls in the camera control panel, watch
focus scores.
Use the Graph tab. Stop when best score
obtained.
Telescope now in focus.
During the Setup Phase, the scores being shown are meaningless as they are changing because of
changing the software parameters, not changing the focus of the telescope.
At the end of the Setup Phase, Reset the Graph to wipe the score history.
During the Focusing Phase, only adjust the telescope's focuser, not any of the settings within
SharpCap – this is to ensure the changes seen in the focus score are only a result of the changes in
focus of the telescope and are not influenced by anything else. If any SharpCap settings are changed
during the focusing stage (for instance because a planetary target has shifted in the field of view and
there is a need to update the ROI), reset the graph after making the adjustment – effectively starting
the focusing phase again.
Focus will need to be checked throughout a session as it could change because of one or more of the
following factors:
•
•
•
•
Thin cloud over target.
Changing atmospheric conditions.
Change in temperature affecting telescope tube.
Change in temperature affecting optics.
The table below shows what would be seen in SharpCap when using the appropriate Calculate Focus
Score tool for a telescope both without and with an ASCOM focuser.
Telescope (no ASCOM focuser)
Telescope (with ASCOM focuser)
Page 106 of 157
SharpCap 2.9 User Manual
FWHM measurement for star. In this trace, the
focuser was moved from a position of
reasonable focus (initial yellow/green bars) to a
position of poor focus (red bars) and back to a
position of good focus (dark green bars). [Note:
History tab only.]
Contrast Edge Detection for a planet. In this
case, the focuser was moved from an initial
poor focus to a better focus and past best focus
back to a poor focus position. [Note: History
and Graph tabs.]
14.5 Overview of Display
When selecting one of the Focus Score tools, Contrast (Edge) Detection in this case, the following
screen appears. This screen layout is the same for all six Focus Score tools.
There are four distinct regions when a Contrast Focus Score tool is in use.
Page 107 of 157
SharpCap 2.9 User Manual
The Capture Display Area
In the Capture Display Area, a red Selection
Area rectangle appears. The rectangle can be
dragged with the mouse and resized. It would
be moved over the edge of the object,
completely onto the surface, or expanded to
surround the complete object.
•
•
•
Any area outside the red rectangle will be
excluded from focus score calculations.
Any area within the rectangle which is not
shaded (above the black level) will be
included for focus score calculations.
Any area within the rectangle which is
shaded (below the black level), will be
excluded from focus score calculations.
The Controls Pane
•
•
The following Controls are available:
o Black Level %, a slider
o Reduce Noise, a checkbox
o Averaging, see description
below
Context sensitive Help is available.
The Graphs Pane
•
•
•
•
•
Page 108 of 157
The graph region will display a graphic
for:
Focus Score history (History tab)
Focus Score v Focus Position graph
(Graph tab). [Note: This only shows if
there is an ASCOM focuser
connected.]
The black line is used to indicate
Focuser Position (explained later).
The blue line is Average Score – an
average of the 10 previous focus
scores.
The left hand vertical axis shows focus
scores.
The right hand vertical axis shows
focuser position.
SharpCap 2.9 User Manual
The Scores Pane
•
•
•
•
The title bar of the panel can be used
to drag the panel out of the main
SharpCap form, for example to place it
on a second monitor
The Pin icon can autohide the focus
tool displayed in the Work Area.
Current score (Now) and Best score
recorded so far (Best) are shown.
The Reset button clears the history
and the best score. If the Selection
Area is enabled, disabled or moved, or
the Black Level changed, the Reset
button should be used.
14.5.1 Focus Tools Controls
This section describes the focus tools controls. At first use, a set of sensible defaults is offered. As
these settings are changed, SharpCap will retain them for subsequent use.
This is a summary of the control group for all six focus score methods. The first five are identical,
with the Bahtinov mask having two additional fields.
Page 109 of 157
SharpCap 2.9 User Manual
Context sensitive help is available with all six focus score tools – click the Help link to see the help
onscreen. For example, this is the Help for Contrast (Edge) Detection:
The controls in the next table are common to all six focus score methods.
Black level – anything below that level is
excluded from the calculation, avoids including
dark level noise in the calculation.
Reduce noise – applies a weak Gaussian blur to
the image to cut down on pixel noise before
performing the measurement.
Averaging – choose either average or best
score from an averaging period to be the value
recorded.
Average Over – the period can be specified as
either number of frames or a time-period by
the settings offered.
Scores – Now and Best are shown. Understand
which focus score methods need high/low
values.
The score can be Reset and should be if the
Selection Area is enabled, disabled or moved, or
the Black Level changed.
Angular Resolution and Line Width are controls found only in the Bahtinov focus score.
Page 110 of 157
SharpCap 2.9 User Manual
Angular Resolution – measured in degrees and
defines how finely to scan the full 360 degrees
when looking for Bahtinov lines – the default
scans once per degree, but it can be made
finer. Possible values are 0.20°, 0.25°, 0.33°,
0.5°, 1.0°
Line width – measured in pixels and should be
set to roughly the width of the Bahtinov spikes
seen on the screen – the correct value here
helps SharpCap separate the spikes from the
noise. Possible values are 1..40 in increments
of 5.
14.5.2 The Graph Pane
The History tab always appears (1st diagram below). The additional Graph tab will only appear when
an ASCOM focuser is connected (2nd diagram below).
14.5.2.1 History Tab
The History tab provides more functionality when there is an ASCOM focuser, although it is best to
switch to the Graph tab when a focuser is connected.
•
•
No ASCOM focuser connected
Page 111 of 157
Blue 'average' line appears,
an average of the last 10
focus score measurements,
helps to see changes when
the focus value is varying
from frame to frame due to
noise.
New measurements appear
on the right, older ones will
disappear from the left
once the chart area is filled.
SharpCap 2.9 User Manual
•
•
•
•
•
•
ASCOM focuser connected
Focuser Position axis on the
right appears.
Black Focuser Position line
appears.
Blue average line changes
to a stepped graph.
Each horizontal segment of
the average line
corresponds to a period
when the ASCOM focuser
was at a certain position.
When the focuser position
moves, a new segment
starts.
The horizontal segments
indicate the average focus
score value over all the
samples when the focuser
was at that certain position.
This is the range of colours that can be displayed – from red (poor focus) to green (good focus).
Red > Orange > Yellow > Light Green > Dark Green
Colours and heights of focus graph bars are not an absolute measure of 'good focus', they are a
measure relative to the other recent focus measurements made. The best focus score recently
obtained will always get a vivid green bar and will be the highest (lowest for FWHM) one in the
graph. This doesn't mean perfect focus, it means the best focus achieved since the focus tool was
opened (or since last reset). The exception to this is the Bahtinov mask tool - there the value of zero
is an absolute measure of perfect focus.
14.5.2.2 Graph Tab
This graph only appears if an ASCOM focuser has been configured in SharpCap.
The graphic shows the focuser position was stepped from -3 to +3 in the following sequence:
-3 -2 -1 0 1 2 3
Page 112 of 157
SharpCap 2.9 User Manual
This graph shows the focuser position along the horizontal axis and the focus score on the vertical
axis.
•
•
•
•
The green upward pointing triangles show data points collected when the focuser was
moving in the positive (outward) direction.
The red downward pointing triangles show data points collected while the focuser was
moving in the negative (inward) direction.
Stronger colours indicate more recent data points.
Faded colours indicate older data points.
The black lines and numbers on the History graph below correspond to the focuser positions shown
in the Graph above.
With an ASCOM focuser installed, work from the Graph tab rather than the Histogram tab. To find
the point of best focus using the focus score axis (at the left of the graph) look for:
•
•
•
The peak value (Contrast Detection/Fourier options).
Minimum value (FWHM options).
Zero (Bahtinov option).
Backlash in the focuser mechanism will be present in all real focusers and shows itself as the best
focus point appearing in differing positions depending on which direction the focuser is moving. So,
if the peak focus score is at focuser position 20100 when the focuser is moving in the positive (+ve)
direction, it could be at 19900 when moving in the negative (-ve) direction. If trying to return the
focuser to the position where the score was at its best, always approach from the same direction
used when measuring the focus to avoid errors caused by backlash.
Page 113 of 157
SharpCap 2.9 User Manual
This functionality can be experimented with using the Focus Offset control available in Test Camera 2
(High Speed) which can be found in the Camera Control Panel.
14.5.2.3 History and Graph Manipulation
• Drag with left mouse button to move around.
• Mouse wheel to zoom.
• Select an area with middle or right mouse button to zoom to that area.
• Double click to return to default view if lost.
Hovering the mouse over the blue line will
show focus score history of the preceding 10
samples.
Page 114 of 157
SharpCap 2.9 User Manual
Hovering the mouse over the
focuser graphics will display a
focuser position and score
report.
14.6 Setting the Correct Black Level
Before setting the black level, ensure the object is not over-exposed by viewing with the Image
Histogram – avoid the Image Histogram hitting the right-hand side.
For a large planetary target, the optimum black level is when there is a thin black area between the
object and the dark area. This can be difficult to see, so use the Zoom tool from the tool bar to
improve the detail.
Contrast (Edge) Detection focus score used.
Here the Zoom is 100%. The black level
happened to be 6.5% in this case.
The actual optimum percentage black level will
vary depending on camera and settings. The
picture illustrates how the black level shading
should look when the black level is set
correctly.
When the ROI is over the planet, and everything within the ROI is part of the desired image. The
requirement is to measure the focus of all of it. Hence in this case, the black level is set to low or
zero.
For a star as target, the optimum black level is when there is a thin black area between the object
and the dark area. This can difficult to see, so use the Zoom tool from the tool bar.
FWHM focus score used.
Here the Zoom is 150%. The black level
happened to be 21% in this case.
The actual optimum percentage black level will
vary depending on camera and settings. The
picture illustrates how the black level shading
should look when the black level is set
correctly.
Page 115 of 157
SharpCap 2.9 User Manual
This is the effect of the correct black level on the focus score, making it clear the graph should
always be reset after adjusting the black level or other parameters to avoid confusing the results of
these adjustments with actual changes in the quality of focus.
14.7 Using a Bahtinov Mask
A Bahtinov mask must be fitted to the telescope for the Bahtinov mask focus score tool to work.
Here are examples of diffraction patterns obtained using a Bahtinov mask in the conventional way,
where the intersection of all three diffraction spikes at a single point indicates good focus.
Good
Off to the left
Off to the right
The Bahtinov Mask is used for single stars, which must be selected with the region selection area.
Good focus is indicated by short green bars. No bars, or a score of 0, indicated perfect focus.
When using the Bahtinov mask tool, ensure the Black Level control is set to a value that excludes the
background area around the diffraction spikes from the focus score calculation but includes the
entire visible diffraction spike area.
Page 116 of 157
SharpCap 2.9 User Manual
SharpCap attempts to detect the diffraction lines created by the Bahtinov mask and calculate
whether they all meet at a single point (in focus) or not – SharpCap will draw coloured lines over the
diffraction spikes as can be seen in the diagrams below.
Check the lines really are following the diffraction spikes, as sometimes the wrong lines will be
detected and if this happens (as shown in the diagram on the right) the focus score will not be
accurate. When the lines are detected incorrectly, it is usually possible to correct the problem by
adjusting the black level or camera parameters such as gain or exposure.
SharpCap overlay
Resulting graphic
Diffraction spikes
Diffraction spikes overlaid by the SharpCap mask gives the aligned graphic at focus.
Page 117 of 157
SharpCap 2.9 User Manual
15 Polar Alignment
Polar Alignment is a new feature in SharpCap 2.9. The idea was inspired by the PhotoPolarAlign
application created by Themos Tsikas. Themos has been kind enough to help with testing and
suggestions during the development of the polar alignment feature in SharpCap.
The Polar Alignment procedure can be started from the Tools menu.
15.1 How does it Work?
The polar alignment works by analysing two pictures taken of the area near the pole. Take one
picture, let SharpCap analyse it, rotate the mount by about 90 degrees about the RA axis and take
the second picture. By recognizing the stars in each of the pictures, SharpCap can work out two
things:
1. The exact area of sky represented in each image - this process is called Plate Solving.
SharpCap has a built-in plate solving algorithm that doesn't need an internet connection or
any other program or database to be installed. SharpCap's plate solving only works within 5
degrees of the pole though (N or S).
2. The centre of rotation about which the stars seem to rotate when going from the first to the
second image.
Since SharpCap has worked out exactly what RA & Dec the telescope was pointing at in each image,
it knows where in the image (or perhaps how far off the image) the celestial pole is. SharpCap also
knows the point about which the stars seem to rotate - that's where the mount’s RA axis is currently
pointing. If those two points are the same, the polar alignment is perfect. If they are not the same,
all that is required is to adjust the Altitude and Azimuth adjusters of the mount until they are the
same point and that will complete polar alignment.
SharpCap will guide through this process with on-screen instructions, including a live update of how
far is still needed to move the mount in each direction to get perfect alignment.
15.2 What is required?
•
•
•
•
•
An equatorial mount.
A camera supported by SharpCap combined with a telescope/finder-scope on the mount.
A field of view in the camera of between 1 degree and about 2.5 degrees. [Note: Newer
versions (2.9, 2.10) can cope down to 0.5 degrees.]
Able to see about 15 stars in the field of view.
To already be aligned within 5 degrees of the pole
It is not required to have perfectly aligned the guider scope or main scope as the polar alignment
process is not affected by this sort of misalignment.
15.3 Step-By-Step
When first selecting the Polar Alignment tool, SharpCap will try to plate solve each frame coming
from the camera. If enough stars are detected and the field-of-view is the right size and close
enough to the pole something like this should be seen:
Page 118 of 157
SharpCap 2.9 User Manual
The stars SharpCap is using to perform the plate solving are highlighted in yellow, other stars are
highlighted in red. The North (or South) celestial pole is shown and circles of different radii are
shown around it. Note that the pole may be out of view - don't worry if it is, carry on to the next
stage.
[Note: the ‘Next’ button will turn green when SharpCap is ready to advance to the next stage and
that the user needs to press the button.]
If the plate solving fails, there are three likely causes:
1. Not enough stars detected.
2. Too far from pole.
3. Field of view too large or too small.
The last two require physical changes to be made to the setup, but the first might be fixable by
adjusting the star detection parameters at the bottom of the screen or by adjusting the exposure or
gain of the camera in use. If the stars are too faint, try turning up the exposure, gain or digital gain.
If hot pixels or noise are being picked up as stars, try turning up the noise reduction control.
Once the first frame is solved, press the NEXT button to move to the next stage.
After pressing NEXT, rotate the RA axis through about 90 degrees. Do this either by unlocking the RA
clutch or by using the mount's GOTO system if it has one.
Page 119 of 157
SharpCap 2.9 User Manual
SharpCap will continue attempting to plate solve each frame - once it manages to solve a frame that
has rotated far enough it will offer the option to move on to the adjustment phase - looking a bit like
this:
At this point, SharpCap has calculated the position in the image that the RA axis is pointing at - this is
the point around which the image appeared to rotate. The RA axis point might be out of view, so
don't worry if it doesn't show up, so long as the 'NEXT' button becomes enabled.
If the 'NEXT' button is not enabled, try different amounts of rotation (or rotating in the opposite
direction). If that still fails, it is likely that not enough stars are being picked up in the rotated
position - the best way to fix this is to leave the mount in the rotated position and press the 'Restart'
button to go back to the start of the alignment process. This leaves a view of the rotated position
with the star detection controls available to play with until a plate solve can be achieved in that
orientation.
DO NOT ADJUST THE ALTITUDE OR AZIMUTH UNTIL NEXT HAS PRESSED TO MOVE TO THE FINAL
STAGE.
Once the button is pressed to move to the adjustment stage, one of the brighter stars on screen will
be highlighted with an arrow pointing to a target, like this:
Page 120 of 157
SharpCap 2.9 User Manual
All that is required to get good polar alignment is to move the indicated star into the target - doing
this will also line up the NCP with the RA axis and polar alignment done. At the bottom of the
screen, below the Polar Align Error figure are some guidelines indicating which direction the mount
needs to be moved. These are calculated based on the estimated longitude which is calculated from
the offset between the local time and GMT, so they are not exact.
During the adjustment phase the highlighted star might switch to a different one - no need to worry,
just keep adjusting. As this gets closer the arrow and target changes to a pair of parallel lines that
need to be brought together to finalise the alignment process.
If it is found that the length of the arrow isn't updating, or is only updating now and then, it is likely
that the plate solving isn't working for every frame - either ignore the problem and just get the star
into the target or alternatively try further tweaks to the gain or exposure to get the star detection
and plate solving working more reliably. That an alignment error of under 2 minutes of arc is
considered good and under 1 minute of arc is excellent. Do not waste time trying to get the
alignment error all the way down to zero.
15.4 Tips
•
•
•
•
Try using a guiding camera (such as ZWO120MC, QHY5LII, Altair GPCAM and others) with a
~200mm focal length finder-guider - this will give the correct field of view.
Read the on-screen instructions - they will walk through the procedure.
Select a high gain and an exposure of 4-8s - this should let SharpCap see enough stars.
If the mount is on a pier, the pier mounting plate bolts can often give finer adjustment than
the mounts own alt/azimuth adjusters.
Page 121 of 157
SharpCap 2.9 User Manual
•
•
Don't worry if the scope or finder is aligned with the mount correctly - misalignment won't
affect the result.
SharpCap needs to know the approximate longitude to work out which direction
(up/down/left/right) the mount needs to be moved. If the time zone is set incorrectly, the
wrong directions may be suggested.
Page 122 of 157
SharpCap 2.9 User Manual
16 Configuring SharpCap
SharpCap configuration is carried out in the Settings dialog, which can be accessed from the File
menu.
16.1 General Tab
16.1.1 Automatically connect to camera when SharpCap starts
When set, SharpCap will automatically reconnect to the last used camera at start-up. If set, this
setting can be overridden by holding down the Control key when starting SharpCap, which will skip
opening a camera at start-up. This setting is enabled by default.
16.1.2 Display in night vision colours
This option is unchecked by default.
Normal vision (day) colours
Night vision colours
Use night vision to preserve dark adaptation of the eyes during a capture session if intending to
observe visually.
Page 123 of 157
SharpCap 2.9 User Manual
16.1.3 Default Zoom
This option has a range of values from 25% - 800%; a sensible default would be 50%.
The Zoom setting gives the ability to zoom in or out of the image in the display area. This feature
can be used to:
• Zoom in when searching for fainter objects.
• Zoom in when trying to place the FX Selection area over a single-star when using the
Calculate Focus Score tool.
• Zoom out to reduce the image size displayed when Live Stack or Histogram are in use.
• Zoom out to reduce the image size displayed when capturing at higher camera resolutions.
The zoom value can also be changed using the Zoom tool on the Tool Bar.
16.1.4 Saved target names
This option is a pre-configured list of object names. Objects can be added to the list or removed
from the list and the list re-ordered.
To add a new object, for example M42 or Whirlpool Galaxy, type the name anywhere into the Saved
target names list. Click Apply to save the amended list. The amended list will be available the next
time SharpCap is started.
The list also appears in the Tool Bar near the top of the screen under Object Name. Objects added in
Saved target names will also appear in the Tool Bar dropdown list.
Page 124 of 157
SharpCap 2.9 User Manual
Examples:
• Object Name undefined (the default), captures saved in folder: YYYY-MM-DD\Capture
• Object Name defined, captures saved in folder: YYYY-MM-DD\Object
• Moon selected as Object Name, captures saved in folder: YYYY-MM-DD\Moon
16.1.5 Show tips when SharpCap starts
This option is checked by default. The Tip of the Day appears when SharpCap is started but can be
disabled for future start-ups here or when SharpCap starts.
16.1.6 Start cameras with ‘Auto’ output format (for supported cameras)
This option is checked by default. For supported cameras, this option will set the Output Format
control into Auto mode when a camera is opened. This does not apply to DirectShow cameras as
they do not have an Output Format control.
16.1.7 Preferred Video Format
AVI is the default video format. This determines the auto selected format in the camera section of
the Camera Control Panel.
16.1.8 Preferred Still Format
PNG is the default still format. This determines the auto selected format in the camera section of
the Camera Control Panel.
Page 125 of 157
SharpCap 2.9 User Manual
16.2 Hardware Tab
This is the hardware screen for a default SharpCap installation. The fields Focuser, Filter Wheel and
Mounts all show as None.
This is the hardware screen when various ASCOM compliant hardware has been configured.
•
This section will only need to be configured if a computer controlled focuser, mount or filter
wheel is to be used from within SharpCap.
•
The ASCOM platform must be installed to be able to select any hardware in this section.
•
Ensure ASCOM drivers for the hardware are installed and configured.
Page 126 of 157
SharpCap 2.9 User Manual
•
The ASCOM platform comes with a range of simulated hardware drivers that can be used for
testing and experimentation.
16.3 Filenames Tab
This tab allows fine control over how captured images and videos are named and organised.
16.3.1 Save captured files to
This allows the top-level capture folder to be selected. All captured files will be saved into this folder
or subfolders created within this folder.
The capture folder in a default installation will be on the logged-in user’s desktop and is called
SharpCap Captures.
The browse button allows other capture folders to be selected or created.
16.3.2 Test Write Speed
This button will carry out a hardware performance test of disk write speed. Running this test will
discover if the camera’s capture rates are being degraded by disk write speeds.
16.3.3 Organise captured files into subfolders
If this is unchecked, all captures will be saved in the top-level capture folder. When checked,
captured files will be saved into subfolders according to the rules selected below.
Options and combinations for folder and file names are available. Sensible defaults are offered in
the initial, default installation. Examples of using the options are given below.
16.3.4 Date and then Target Name
Below is an example of a saved file organised by date then target name. File names are derived from
the creation time of the capture and are in the format HH_MM_SS. Note the higher-level directory
is named after the date and the inner directory named after the target.
Page 127 of 157
SharpCap 2.9 User Manual
16.3.5 Target Name and then Date
Below is an example of a saved file organised by target name then date as seen in the Notification
Bar (green = success). Note the higher-level directory is named after the target and the inner
directory named after the date.
16.3.6 Create WinJUPOS Compatible File Names
Below is an example of a saved file using a WinJUPOS compatible name – a combination of date and
time. This uses mid-point time in the capture for the WinJUPOS name. Using this option will make
loading video files into WinJUPOS for de-rotation easier.
16.3.7 Use UTC times in files and folder names
When this option is checked, all dates and times used for filename generation will be UTC times.
When it is unchecked, local times will be used.
Below is an example of a saved file using the UTC time format.
The letter designates time zone, Z = United Kingdom.
Page 128 of 157
SharpCap 2.9 User Manual
16.3.8 Use sortable date format (YYYY-MM-DD)
When checked, the date format YYYY-MM-DD will be used for all dates, making it easy to sort file
and folder names in Windows Explorer. When unchecked, the date formatting rules appropriate to
the PC’s regional settings will be used. This option is checked by default.
16.3.9 Save capture settings file alongside each capture
When checked, each capture file will, have an associated settings file saved with it.
22_06_22.avi & 22_06_22.CameraSettings.txt
The text file to the right contains capture
settings from the Camera Control Panel – useful
for reference in future observing sessions or
analysis during a post-processing session.
The name of the text file reflects the time of
creation.
The captured data (video or still) and the
CameraSettings.txt file will have the same
timestamp in their filenames.
16.4 Start-up Scripts Tab
This tab allows a list of Python scripts, to be run at SharpCap start-up, to be configured. Such scripts
can be used to add additional features or customizations to SharpCap every time it is started. Use
the Add, Remove, Move Up and Move Down buttons to manage the list of start-up scripts.
For example, the following Script will create a button on the toolbar that selects the first camera
when pressed. The code can be created and saved by following the information in Scripting.
def selectFirstCamera():
SharpCap.SelectedCamera=SharpCap.Cameras[0]
SharpCap.AddCustomButton("Test", None, "Select the first camera", selectFirstCamera)
Save the script somewhere (call it SelectFirstCamera.py for example), say on the desktop and
configure File > SharpCap Settings > Startup Scripts accordingly.
Page 129 of 157
SharpCap 2.9 User Manual
Deselect the camera, restart SharpCap and the button Test should be added to the right-hand end of
the Tool Bar, together with the camera having been selected.
This technique is good to use for the start-up script as it allows creation of custom toolbar buttons
and have them load every time SharpCap is started.
The Test button can be removed via File > SharpCap Settings > Startup Scripts, highlighting the script
SelectFirstCamera.py, selecting Remove and restarting SharpCap.
Page 130 of 157
SharpCap 2.9 User Manual
17 Capturing and Using Dark Frames
Images taken with digital cameras can suffer from noise caused by the camera sensor and
electronics. Dark frames can be used to counteract the effect of this noise on image quality. A dark
frame is taken with the camera lens (or telescope) covered to ensure there is no light – this means
any signal in the dark frame is due to noise. Once a dark frame has been created, it can be
subtracted from each image frame to remove much of the noise. The dark frame must be captured
under identical conditions (such as exposure, gain, resolution, temperature) as the image frames for
the noise to cancel correctly.
Some cameras have a Peltier thermoelectric cooler attached (a fridge on the back of the camera) to
combat noise generated by heat from long exposures.
17.1 Camera Noise
Below are examples of camera noise.
Amp glow in bottom right-hand corner – image
produced with a webcam. This amp glow can
be removed from an image by using dark frame
subtraction.
Thermal noise – image produced with a colour
astro video camera. This thermal noise can be
removed from an image by using dark frame
subtraction.
The brightest dots are hot pixels – produced
with a monochrome camera and a high gain
setting. With a colour camera, the hot pixels
would appear as differing colours. These hot
pixels can be removed from an image by using
dark frame subtraction.
Page 131 of 157
SharpCap 2.9 User Manual
A dark frame is captured to subtract it from later frames, to remove as much of the camera noise as
possible.
17.2 Dark Frames Explained
SharpCap can capture a dark frame – the result being stored in the default capture folder under
darks.
The dark frames must be captured using the same resolution and colour space as the image about to
be captured. The same exposure and gain values should be used for the darks as for the captured
images and ideally the temperature of the camera sensor should be the same to ensure the noise in
the dark frame is as far as possible the same as the noise in the light frames
SharpCap can subtract dark frames for DirectShow cameras within Live Stack, for other cameras this
subtraction is carried out in the Camera Control Panel or with post-processing software. Below is an
example of the dark frame subtraction process and how it impacts the final image.
Captured frame
Initial image from the camera,
showing noise (magnify document
to see the noise more clearly).
Subtract
Dark frame
Dark frame image generated by
SharpCap. The camera must be
capped off or the cover put on the
telescope to generate this.
Equals
Page 132 of 157
SharpCap 2.9 User Manual
Final image
Most of the camera noise has
been removed. The subtraction of
the dark frame is done within
SharpCap.
17.3 Capture Dark Dialogue
This subsection explains the process for capturing and saving a dark frame. The process is started
from the main menu via Capture > Capture Dark. The telescope or camera must be covered to
exclude any light before commencing the dark frame capture.
While the Capture Dark Frame window is open, do not use any SharpCap functions. Additionally,
while the darks are being captured (after pressing the Start button), do not adjust any camera
controls. Once the window closes, the dark frame capture process has completed.
Using the Test Camera 1 (Deep Sky) and the settings above (10 frames), a folder structure is created.
The folder structure represents the camera settings in the Camera Control Panel.
Page 133 of 157
SharpCap 2.9 User Manual
In the folder gain_100 the following dark frame set is stored:
This is an example of a dark frame. The white points are hot pixels and notice the green-blue
mottled background – to best see this, magnify the document to at least 150%.
The dark frame should be applied against a capture (light) which has the same properties as the
dark. Ideally, the dark frames should be captured at the same time as the image is captured to
ensure settings and camera temperature are matched.
The FITS file produced can be opened by suitable software – an example of which is FITS Liberator.
Page 134 of 157
SharpCap 2.9 User Manual
18 Scripting
SharpCap has a scripting language built in that allows simple programs to be written that can
perform just about any action that can be performed when controlling SharpCap with the keyboard
and mouse. The scripting language is based on a language called IronPython which is a Microsoft
port of the Python Programming Language to the .NET framework.
18.1 The Scripting Console
The Scripting console can be shown by selecting Show Console from the scripting menu. The
scripting console is an Integrated Development Environment (IDE). This allows for the creation,
execution and debugging of code using the IronPython programming language and its integration
into SharpCap.
Typing help() and <ENTER> into the IronPython Console window gives the following basic help
output:
Page 135 of 157
SharpCap 2.9 User Manual
Some examples are displayed. One of these is code to list the cameras available to SharpCap.
#List the cameras available
print SharpCap.Cameras
Lines beginning with # are comment lines, meaning they are ignored by the computer.
Code can be typed directly into the console or pasted into the IronPython Pad in the lower part of
the console window. If code is typed into the upper part of the window, it will be run when the
<Enter> key is pressed. Longer sections of code should be typed into the lower editor area where
they are not run until the ‘Run’ button is pressed.
Controlling SharpCap is handled using the SharpCap object which is automatically loaded into each
script session. Some simple commands would be...
SharpCap.SelectedCamera = None # Close the camera that is currently active
SharpCap.SelectedCamera = SharpCap.Cameras[0] # Open the first camera in the Cameras menu and start
previewing it
Once a camera is running, adjust its properties like this
SharpCap.SelectedCamera.Controls.Exposure.Value = 1000 # Set the exposure to 1000ms (1s)
In the IronPython Pad, type in the code print SharpCap.Cameras and press the Run button.
The following output appears in the IronPython Console.
Page 136 of 157
SharpCap 2.9 User Manual
Click the floppy disk icon and save the file as cameras.py for use in the Run Script menu item below.
Exploring the API
The editor automatically shows the possible methods and properties for an object upon typing the '.'
– this helps explore the available API.
In the IronPython Console, type the following two lines (the case of the text matters and the ‘.’
matters):
import System
from System.
As soon as the ‘.’ is typed, a list appears allowing selection. This trick can be applied to many parts of
the SharpCap API to allow discovery of the methods available and what parameters they require.
18.2 Run a Script
The Run Script menu item opens a File Explorer window to allow selection of a previously created
Python script.
Scripts (programs) can also be created from within Windows using any text editor. The scripts must
be saved with a .py extension.
Page 137 of 157
SharpCap 2.9 User Manual
From the Menu select Scripting > Run Script.
Browse to the file something.py and click the Open button. The script should execute.
Example
1. From the Menu select Scripting > Show Console.
2. Drag the Iron Python Console to one side using the mouse.
3. From the Menu select Scripting > Run Script.
4. Navigate to the file cameras.py, created in the previous section, and select it.
5. The script executes and the result (the available cameras) is shown in the IronPython
Console.
The above example has no practical use but serves to demonstrate how to use SharpCap
functionality.
18.3 Scripting Tutorial
18.3.1 Create a Script
This section shows how to:
• Create a simple script using the IronPython Console.
• Save the script.
• Run the script from within the console.
• Run the saved script directly from the Run Script menu option.
Upon selecting Show Console, an Integrated Development Environment (IDE) is displayed. This
allows for the creation, execution and debugging of code using the IronPython programming
language.
Page 138 of 157
SharpCap 2.9 User Manual
The code below will capture a single PNG image and save it to a file. The destination d:\capture.png
will need to be changed to somewhere convenient on the computer being used.
SharpCap.SelectedCamera.CaptureSingleFrameTo("d:\capture.png")
Complete the following steps to test the scripting functionality:
1. Start SharpCap and from the Menu select Cameras > Test Camera 1 (Deep Sky).
The M42 image should be shown in the Capture Display Area.
Page 139 of 157
SharpCap 2.9 User Manual
2. In the Camera Control Panel, change the Output Format to be PNG files…
3. From the Menu select Scripting > Show Console.
The IronPython Console will open.
4. Copy the following code:
SharpCap.SelectedCamera.CaptureSingleFrameTo("d:\capture.png")
and paste it with Ctrl+V (or type directly) into the IronPython Pad (bottom part of the
IronPython Console). Edit the destination (underlined in red) to be something appropriate
on the PC in use.
Page 140 of 157
SharpCap 2.9 User Manual
5. Press the Run icon (or F5).
6. Check the destination which, all being well, should now contain 2 new files called
capture.png and capture.png.CameraSettings.txt.
7. Edit the code to change the capture file name to be capture2.png.
8. Click on the floppy disk icon and a file explorer window opens.
Save the file as capture2.py (the .py extension is important).
[Note: there is a bug in SharpCap prior to version 2.9.3055 which causes the file to be
saved as capture2.py.txt. The file must be renamed to capture2.py (the .txt will not be seen
unless File name extensions is checked in File Explorer).]
9. Close the IronPython Console.
[Note: Of course, the point of scripting is to automate the use of SharpCap, and all of the above
steps could be automated by a more complex script – for example:
SharpCap.SelectedCamera = SharpCap.Cameras.Find( lambda x:x.DeviceName == "Test Camera 1 (Deep Sky)")
SharpCap.SelectedCamera.Controls.OutputFormat.Value = "PNG Files (*.png)"
SharpCap.SelectedCamera.CaptureSingleFrameTo("d:\capture.png")
Page 141 of 157
SharpCap 2.9 User Manual
18.3.2 SharpCap Scripting Object Model Reference
The major objects available to control the application are:
SharpCap
The main application object, all other objects are accessed
via this object.
SharpCap.Cameras
A collection of available cameras (as shown in the Cameras
menu)
SharpCap.SelectedCamera
The camera that is currently open (or 'None' if no camera
open)
SharpCap.SelectedCamera.Controls
The controls available on the currently open camera. Many
common controls can be access directly, but others will need
a check of each item in the array to find the control needed.
SharpCap.Focusers
A collection of (ASCOM) focusers detected by SharpCap.
SharpCap.Focusers.SelectedFocuser can be used to connect
to a specific focuser and then access it via the
SelectedCamera.Controls collection.
SharpCap.Mounts, SharpCap.Wheels
Collections of ASCOM mounts and filter wheels, work in the
same way as Focusers.
SharpCap.Transforms
A collection of frame transforms that can be applied to the
preview window by setting the
SharpCap.Transforms.SelectedTransform property (buggy at
the moment)
SharpCap.MainWindow
The main application window of SharpCap. Take care
changing properties or calling methods on this as it may
break things.
SharpCap.Reticules
Collection of reticule overlays that may be selected for
drawing on the screen (like the transforms, also currently
buggy)
SharpCap.Settings
All application settings, alter with care and call 'Save()' after
any changes to make them take effect
In general, the most used objects will be SharpCap.SelectCamera and SharpCap.SelectCamera.Controls.
18.3.3 The Camera Object
The most important methods and properties on the SelectedCamera object are (informational
properties will work on other non-selected cameras):
CanCapture, CanStillCapture
Indicate whether the camera can capture video and still frames,
respectively
CanPause
Can the camera pause a video capture without stopping it?
CaptureConfig
Settings controlling the type of capture to be performed, including
frame limit, etc
Page 142 of 157
SharpCap 2.9 User Manual
PrepareToCapture()
Must be called to set up a video capture before calling
RunCapture()
RunCapture()
Begins a prepared video capture. The capture will run until any
limit is reached or StopCapture() is called. The output file(s) will be
named according to the selected naming scheme.
CancelCapture()
Cancel a capture that has been prepared (instead of running it
using RunCapture).
CaptureSingleFrame()
Capture a single frame snapshot (the output file will be named
according to the selected naming scheme
CaptureSingleFrameTo(string
filePath)
Capture a single frame and save it to the specified output file
name. The path will need to be a full path and the extension
specified should match that selected in
SharpCap.SelectedCameras.Controls.OutputFormat.Value
Name
The name of the camera used in the application UI
VideoDeviceId
In internal identifier for the camera (may be empty or rather
geeky)
StartPreview(), StopPreview()
Start and Stop previewing frames on the camera respectively
RestartPreview()
Stop then re-start previewing frames on the camera
GetStatus(boolean allStats)
Returns an object describing the status of the camera including
frames captured, average frame rate, etc.
IsOpen, IsPreviewing,
CanCountFrames, Capturing
Informational properties, as named
CapturedFrameCount
The number of frames processed by the camera (including preview
frames) since the last time preview was started or capture was
started or stopped.
ApplySelectedTransform()
Reserved, internal use only
The following controls may be available directly on the Controls object for the SelectedCamera:
Binning, ColourSpace, Exposure, FilterWheel, Focus, Gain, OutputFormat, Resolution
Other controls are likely to be available within the Controls collection and must be searched for by
name, for example:
cooler = SharpCap.SelectedCamera.Controls.Find(lambda x: x.Name == "Cooler")
Note that the available controls vary from camera to camera, and only ColourSpace, Exposure,
Resolution and OutputFormat are always available.
Page 143 of 157
SharpCap 2.9 User Manual
18.3.4 The Control Object
The following properties are available on each Control:
Available
True if the control is actually available to read or write values.
ReadOnly
True if the control can only be read from (for instance a sensor temperature
readout)
AutoAvailable
True if the control can be set into Auto mode
Auto
Switch the control between Auto and Manual mode
Name
The name of the control as displayed in the UI
Id
An enumeration of common property types, currently including: Other,
Exposure, FrameRate, Pan, Tilt, Resolution, ColourSpace, OutputFormat,
Focus, FilterWheel, FrameFilter, Binning, Gain
Minimum, Maximum Retrieve the minimum and maximum values of numeric controls
Step
Integer controls may have a step value defined - they can only be changed in
multiples of this value. This is very rarely encountered.
Value
The value of the control, which can be retrieved and (if not ReadOnly)
changed.
Type
The type of value that the control has.
AvailableValues
Integer
Numeric, whole number values
Double
Numeric, whole or decimal values
Boolean
On/Off value (checkbox)
Command
A single action, launched by a button in the UI
MultipleChoice
A list of options, shown as a drop down control in the UI
Custom
Any other type of control.
In the case of a MultipleChoice control, a list of the choices available.
18.4 Scripting Samples
Examples of scripting tasks are shown below.
Page 144 of 157
SharpCap 2.9 User Manual
18.4.1 Periodic Capture and Timestamp Image
The code below will capture a single PNG image approximately every 15 seconds and write a
timestamp into the image itself before saving it. It would be simple to modify the code to save each
timestamped image under a different filename or to remove the timestamping step.
The code relies on a camera already being selected and previewing and that the camera can output
to PNG files (i.e. will not work if the camera is in a 12/16-bit mode).
import time
clr.AddReference("System.Drawing")
import System.Drawing
SharpCap.SelectedCamera.Controls.OutputFormat.Value = 'PNG files (*.png)'
if (SharpCap.SelectedCamera.Controls.Exposure.AutoAvailable):
SharpCap.SelectedCamera.Controls.Exposure.Automatic = True
while True:
SharpCap.SelectedCamera.CaptureSingleFrameTo("d:\capture.png")
time.sleep(1)
bm = System.Drawing.Bitmap("d:\capture.png")
g = System.Drawing.Graphics.FromImage(bm)
f = System.Drawing.Font("Arial", 12)
g.DrawString(System.DateTime.Now.ToString(), f, System.Drawing.Brushes.Red, System.Drawing.Point(0,0))
g.Dispose()
f.Dispose()
bm.Save("d:\\timestamped.png")
bm.Dispose()
# do more with png file here
time.sleep(15)
18.4.2 Controlling the Selection Rectangle
Before starting this example, select either a suitable Focus Score method or the Image Histogram to
enable the Selection Area generated by the program to be shown. The Selection Area needs to be
turned off via its Tool Bar icon
From Scripting > Show Console, type the following code into the IronPython Console. Do not copy
and paste as this negates the purpose of the exercise. At certain places, when ‘.’ is typed a
dropdown will appear showing possible methods and properties. Select the appropriate text.
import clr
clr.AddReference("System.Drawing")
from System.Drawing import Rectangle
SharpCap.Transforms.AreaSelection = True # turn on selection area
SharpCap.Transforms.SelectionRect = Rectangle(100,200,300,400) # adjust selection rectangle, parameters are
(x, y, width, height)
The typed in code should look like this. When run, nothing will appear to happen except an
additional >>> will appear in the console. No errors messages is a good sign.
Page 145 of 157
SharpCap 2.9 User Manual
This enables use of the .NET type System.Drawing.Rectangle which is required to specify the selection
area - the first 3 lines, which allow access to the .NET type, are the important ones here as they can
be used for other .NET types too.
18.4.3 Example Task to Script
Consider the following non-trivial task.
•
•
•
•
•
•
•
•
Control a USB filter wheel containing LRGB filters
Capture 10x5 minute exposures using L filter
Switch to R filter
Capture 10x5 minute exposures using R filter
Switch to G filter
Capture 10x5 minute exposures using G filter
Switch to B filter
Capture 10x5 minute exposures using B filter
Total capture time = 3h 20m but no intervention is needed if the capture is managed by a script.
Page 146 of 157
SharpCap 2.9 User Manual
19 ASCOM Hardware Control
19.1 Focuser Control
The focuser can be controlled by using the In and Out buttons. Between each pair of buttons (coarse
and fine) are the step size adjustment controls which allow the amount of movement per button
press to be adjusted. The current position of the focuser is shown and it is also possible to directly
type a new position value into this control (after typing a new value press <Tab> or <Enter> to move
the focuser to the typed value). The Reverse checkbox swaps the meaning of the In and Out buttons
- handy if the focuser moves in when pressing Out.
19.2 Filter Wheel Control
ASCOM Filter Wheels are simple to control in SharpCap – the drop-down control shows a list of
filters available and all that is necessary is to select the desired filter from the list. It is best to avoid
trying to change the filter again while the wheel is still moving. The names of the filters shown by
SharpCap can usually be configured in the ASCOM driver configuration dialog for the filter wheel.
As with all ASCOM hardware in SharpCap it is possible to temporarily disconnect from the device by
unchecking the Connected checkbox and the ASCOM driver configuration can be shown by pressing
the Setup button.
19.3 Mount Control
SharpCap can connect to most ASCOM mounts (unfortunately, if the mount does not support the
ASCOM MoveAxis functionality SharpCap will not be able to use it).
On the left-hand side of the control, the current Azimuth, Altitude, RA and Dec are shown – these are
updated from the mount on a regular basis, so should update if the mount is moved using another
application such as a planetarium program.
The centre section of the control is home to the movement buttons which allow the mount to be
moved from within SharpCap. The up, down, left and right buttons will move the mount in the given
direction while they are pressed. If the mount is an equatorial mount, Up/Down will move the
Page 147 of 157
SharpCap 2.9 User Manual
mount in Declination and Left/Right will move the mount in RA. The mount will be moved at a speed
that can be selected using the Rate drop down in the top-right of the control. This lists the
movement rates that the mount makes available (this drop down shows slower movement rates in
multiples of Sidereal rate – i.e. 1x, 2x, 8x – and faster rates in degrees per second). The STOP button
between the direction buttons will stop any current movement of the mount but is not normally
needed as movement is stopped when the direction buttons are released.
The Spiral Search button (top left of the button group) moves the mount in a growing square spiral
around the starting point while it is held down. This is useful when trying to locate an object such as
a planet that may be just out of frame. Note that like the movement buttons, the speed of
movement of the Spiral Search is governed by the Rate dropdown. If the Spiral Search button is
released the spiral movement will stop. Pressing it again will begin a new spiral around the current
location – it will not resume the previous spiral pattern.
Finally, the Tracking button (bottom right) can be used to turn sidereal rate tracking of the mount on
or off. If tracking is turned off, stars and other objects will appear to drift across the field of view.
As with all ASCOM hardware in SharpCap it is possible to temporarily disconnect from the device by
unchecking the Connected checkbox and the ASCOM driver configuration can be shown by pressing
the Setup button.
Page 148 of 157
SharpCap 2.9 User Manual
20 Bugs & Crashes
Before reporting a bug or other issue make sure the latest version of SharpCap is being used as the
bug could have been fixed already. Also, search the forums for other users reporting the same issue
as there may already be a workaround available.
Forums for reporting Bugs and Crashes and other discussions of SharpCap can be found at
http://forums.sharpcap.co.uk .
20.1 How to Report a Bug
If discovering a bug in SharpCap that doesn't involve SharpCap crashing, post the following details in
a new thread in the forum:
•
•
•
•
A thread subject briefly describing the problem.
A description of what was trying to be done.
A list of the steps needed to make the bug happen.
The contents of the SharpCap log collected after the problem has occurred.
Since the log text can be rather long, post it as an attachment rather than including it in the body of
the post.
While SharpCap is running, the log text can be obtained via File > Help > Show Log. Logs are also
saved in the folder %LOCALAPPDATA%\SharpCap\logs.
Alternatively, access the folder C:\Users\<user name>\AppData\Local\SharpCap\logs to find the log
file after SharpCap has been closed.
20.2 How to Report a Crash
20.2.1 Submitting a Crash Report
If SharpCap crashes, it is most likely a message will be displayed requesting a bug report to be
submitted.
Page 149 of 157
SharpCap 2.9 User Manual
If connected to the internet, press the Send and Quit button and the bug report will automatically be
uploaded to the SharpCap bug archive. Optionally, add a description of what was taking place when
the crash happened.
If not connected to the internet, press the down arrow next to Send and Quit which shows extra
options including sending the bug report by email and saving it as a file which can be shared on the
forums.
•
•
•
Upload to S3 Bucket – the default action when pressing Send and Quit, report is uploaded to
the internet.
Send via Email – when connected to internet.
Send report manually – the generated report will be saved as a zip file ready for manual
submission to the forums.
The bug report contains a description of the problem causing SharpCap to crash and the contents of
the SharpCap log, both of which help track down the problem causing the crash.
20.2.2 No Crash Report?
On rare occasions SharpCap may crash without showing the error report message. If this happens,
tracking down the bug requires SharpCap to be re-run from a command prompt with a /dump option
added to the command line like this:
"c:\Program Files (x86)\SharpCap 2.9\SharpCap.exe" /dump
Once SharpCap has been run this way, try to make the crash happen again. If the crash happens, a
file called SharpCap.dmp will be created on the desktop. Post on the forums including a link to the
SharpCap.dmp file and a description of what was being done when the crash occurred. Dump files
can be large, so provide a link to the upload – Dropbox, Google Drive and Microsoft’s One Drive are
useful technologies here, there may be others.
Page 150 of 157
SharpCap 2.9 User Manual
21 Trouble Shooting
This section is inspired by problems encountered.
21.1 Hardware
A common source of hardware problems relating to image capture can be attributed to a lack of
understanding of the USB standards. See https://en.wikipedia.org/wiki/USB for further information
and maximum cable lengths.
Some definitions:
•
•
•
•
•
•
•
•
The USB 2.0 standard defines a High Speed (HS) of 480 Mbits/s.
The USB 3.0 standard defines a SuperSpeed (SS) of 5 Gbits/s, although because of timing
overheads, a data throughput of 3.2 Gbits/s is deemed reasonable.
A passive USB extension cable is a simple cable without electronics.
An active USB extension cable contains electronics to regenerate the USB signal. It is
basically a hub and cable combined.
An unpowered USB hub draws its power from the computer’s USB port.
A powered USB hub has its own external power supply.
Black USB ports on a PC/laptop indicate a USB2 connection is available.
Blue USB ports on a PC/laptop indicate a USB3 connection is available.
Things to consider:
•
•
•
•
•
•
•
A camera will draw its power from the computer’s USB port.
A camera with a cooling fan will draw even more power from the computer’s USB port.
Lack of power can cause a USB3 device to fall back to USB2 speeds.
A low quality (or damaged) USB cable can cause problems.
A copper clad aluminium (CCA) USB cable can cause problems.
Not all USB ports are equal; think here of front USB ports on micro/mini PCs or laptops
running off battery. In case of unexplained difficulty, try different ports on the same
computer.
If an internal PCI USB card has a power connector, ensure an internal power lead is
connected.
USBTreeView is a useful utility for discovering the speed at which a USB connected device is
performing. The utility will show speeds as HS (High Speed = USB2) or SS (SuperSpeed = USB3).
For trouble free running, consider the following:
•
•
•
•
Use the camera manufacturer’s supplied USB cable. If problems arise always test with at
least two different short USB cables to rule out USB cable/hub issues.
If extra length is required, good-quality passive extension cables are usually sufficient up to
3.5m total length for USB3 speeds and 4.5m for USB2 speeds.
Beyond these lengths, the use of hubs or active cables are required.
If running two or more devices from a USB hub consider a powered hub rather than an
unpowered hub.
Page 151 of 157
SharpCap 2.9 User Manual
21.2 Software
•
•
Ensure correct hardware drivers are installed and are up-to-date. Not having the correct
drivers for the installed graphics card installed can lead to the card running in low
performance ‘compatibility mode’ and to slow frame rates or crashes.
Windows ‘N’ variants (which do not have media features installed by default) may require
the ‘Windows Media Feature Pack’ to be installed before SharpCap will work correctly for
certain cameras.
21.3 Imaging
21.3.1 Image Too Bright
Problem – some moons of Jupiter are in my image but the planet has no features.
Solution – the exposure setting on the camera is too high. Reduce the value of Exposure in the
Camera Control Panel until the features of the planet can be seen (the moons might not be visible).
Capture a video of say 1,000 frames. Stack this, for example with AutoStakkert, so hopefully the
moons re-appear on the stacked final image. This is also an argument against cropping too early in
the process as the moons, although not visible in the video, will appear in the processed image.
21.3.2 Jumpy AVI Will Not Stack
Follow these instructions to attempt to rescue a jumpy video created during windy conditions.
The problem – a jumpy surface video (lunar/solar) will not stack.
The solution – have a look at the image stabilisation process at the PIPP website.
21.3.3 Grainy Image
The problem – a very grainy image.
The solution – turn down the Gain in the Camera Control Panel.
Page 152 of 157
SharpCap 2.9 User Manual
This image is of M92, the Owl Nebula, a faint planetary nebula in the constellation of Ursa Major.
Lower the gain and use Live Stack to build a better image.
21.3.4 Histogram with Gaps
Below is an example of a histogram with gaps.
The problem – vertical bars and gaps appear in the histogram.
The solution – it is best to set the white balance back to default (remove the gaps in the histogram)
and to correct the colour balance after stacking. This will avoid the data loss caused by applying
digital white balance correction in SharpCap.
21.3.5 Colours are Wrong
Below is an example of a real world broken histogram and what needs to be done to improve it.
The problem – the colour looks wrong.
The solution – run up the Image Histogram from the Tool Bar. The LRGB histograms should be
reasonably aligned but they are not. In the Camera Control Panel look for White Balance or Colour
Balance and adjust as necessary until the four histograms are roughly aligned – achieved when the
horizontal bars line up at each end.
This capture was taken using an AVS DSO-1 analogue video camera with USB2 video capture device.
The video grabber is classed as a DirectShow device – no camera controls are exposed in SharpCap –
so adjustments are made using the camera’s internal menu. In this type of camera, green would be
adjusted by changing Red and Blue.
Page 153 of 157
SharpCap 2.9 User Manual
Page 154 of 157
SharpCap 2.9 User Manual
22 Appendix
22.1 Test Write Speed
The following data is a summary of Test Write Speed carried out on various hardware configurations.
The Test Write Speed button can be found via File > SharpCap Settings > Filenames tab. Notice the
wide variance in Mb/s and frames per second with the various hardware.
Expect to see a spinning circle while the test is in progress (there is no visible feedback during the
test). At the end of the test the results are displayed:
This test showed a write rate of 215Mb/s (on a 10,000rpm Western Digital Raptor drive running on a
Quad Core Xeon processor motherboard with 16Gb of memory). The platform was Windows 10 Pro
64-bit. Results will vary here depending on hardware capability.
This table compares the performance of various hardware configurations. All tests wrote out 4,882
frames at 1280 x 960.
Hardware
Processor
HP Z220
Xeon Quad
Workstation Core, 3.4GHz
Memory
16Gb
Hard Drive
500GB SATA2,
10,000 rpm
Page 155 of 157
Operating
System
Windows 10 Pro,
64-bit
Test Results
Mb/s
215
*fps
184
SharpCap 2.9 User Manual
ThinkPad
W510
laptop
i7 Quad Core,
1.73GHz
16Gb
500Gb SATA2,
7,200rpm
Windows 10 Pro,
64-bit
240
205
ThinkPad
T400 laptop
Core 2 Duo,
2.4GHz
8Gb
240Gb SATA2
SSD
Windows 10 Pro,
64-bit
191
163
ThinkPad
X61 laptop
Core 2 Duo,
1.86GHz
4Gb
(3Gb
usable)
120Gb SATA2
SSD
Windows 10 Pro,
32-bit
97
83
Linx 10
Tablet
Atom Z3735F,
1.33GHz
2Gb
32GB eMMC
Windows 10
Home, 32-bit
44
38
Note: *fps = frames per second
Consider the hardware demands when purchasing high frame rate cameras.
22.2 SharpCap Uninstall Clean-up
After uninstalling SharpCap the following steps can, optionally, be carried out.
[Optional] Remove Profile data (if created) – profile data is stored in
%APPDATA%\rwg\SharpCap\CaptureProfiles . Navigate to this folder from Search or Run and delete
the contents of the CaptureProfiles folder.
The step below can be omitted but is included for completeness. Always backup the registry before
making changes to it.
[Optional] Remove Registry Entry – run Regedit. Export the registry as a precaution. Navigate to
HKEY_CURRENT_USER\SOFTWARE\RWG\SharpCap and delete the 2.9 key.
22.3 Maintenance of Capture Profiles
When a new capture profile, say Jupiter RGB32, is created, the following happens:
1. A text file called Jupiter RGB32 (name of active camera>.ini) will be saved in the folder
%APPDATA%\rwg\SharpCap\CaptureProfiles.
2. The location of the stored profiles can be accessed by copying and pasting
%APPDATA%\rwg\SharpCap\CaptureProfiles into the Windows search bar. This would be
the way to delete unwanted capture profiles.
Page 156 of 157
SharpCap 2.9 User Manual
23 Useful Software
•
•
•
•
•
•
•
•
•
AutoStakkert!2, for alignment and stacking of image sequences.
DeepSkyStacker, pre-process deep sky pictures.
FITS Liberator, image processing for FITS files.
GIMP, image manipulation, 16/32-bit in v2.10 to be released 2017.
Image Composite Editor, Microsoft’s image stitching software to create mosaics.
PIPP, pre-process planetary images (plus solar & lunar).
Registax, image stacking and wavelet filters.
SER Player, video player for SER files.
VirtualDub, split AVI video into individual frames (think ISS video here).
24 Glossary
ASCOM provides a standard interface to a range of astronomy equipment including mounts,
focusers and imaging devices and runs on the Microsoft Windows platform. Further information can
be found at the ASCOM Standards website.
FITS file format is an open standard adopted by the astronomical community for data storage.
Detailed information can be found at https://fits.gsfc.nasa.gov/fits_documentation.html .
PLATE-SOLVING A software tool to calculate where in the sky an image is from the pattern of stars in
the image. All Sky Plate Solver is an example of this type of software and can automatically detect
the celestial coordinates of captured FITS and JPEG files.
UTC Universal Coordinated Time – the global standard for measuring time in a time-zone
independent way. In practice UTC times are the same as GMT times. See
https://en.wikipedia.org/wiki/List_of_UTC_time_offsets for a description of UTC Time Offsets.
WinJUPOS A software tool to help improve images of Jupiter and other planets by digitally
correcting for the effects of planetary rotation. See http://jupos.privat.t-online.de/index.htm for
information to assist with the processing of image captures of Jupiter.
Page 157 of 157
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertising