Orion® Premium 190mm f/5.3 Maksutov

instruction Manual
Orion® Premium 190mm
f/5.3 Maksutov-Newtonian
Providing Exceptional Consumer Optical Products Since 1975
Customer Support (800) 676-1343 • E-mail: support@telescope.com
Corporate Offices (831) 763-7000 • 89 Hangar Way, Watsonville, CA 95076
IN 370 7/09
Finder scope
dovetail base
mirror cell
Figure 1. The Premium 190mm f/5.3 Maksutov-Newtonian Astrograph optical tube assembly.
Congratulations on your purchase of an Orion ®
Premium 190mm f/5.3 Maksutov-Newtonian
Astrograph. Your 190mm Mak-Newt Astrograph is
designed to deliver a flat field across the field of
view of an APS (advanced photo system) size camera sensor, such as the StarShoot™ Pro or DSLR
imager. Coma is reduced considerably when compared to a Newtonian of equivalent focal length.
The exceptional optical and mechanical quality
of your 190mm Mak-Newt will provide you with a
pleasing telescope experience. The optics are rigidly secured in place to reduce image shift; and diffraction is minimal because the secondary mirror is
held by the corrector glass, eliminating the need for
spider vanes.
Parts List
Optical Tube Assembly
Optical tube dust cover
1.25" eyepiece adapter
Camera adapter
2.5mm hex key
Phillips screwdriver
Collimation cap
Getting Started
Your 190mm Mak-Newt arrives fully assembled from the factory. The optics have been collimated, however you should
check the telescope collimation to ensure the collimation held
after it was shipped to you (see “Collimation”).
We recommend keeping all of the original packaging. In the
unlikely event you should need to ship the telescope back to
Orion for warranty repair service, you should use the original
packaging to ensure the telescope stays intact during shipping.
Take a moment to inspect the telescope and all of its parts.
Using 1.25" and 2" Accessories
Your 190mm Mak-Newt can accommodate both 1.25" and
2" accessories, including just about any eyepiece or camera.
The Crayford focuser has a 2" eyepiece holder with a 1.25"
eyepiece adapter installed. Both the 2" eyepiece holder and
1.25" eyepiece adapter feature a brass compression ring to
hold your accessories in place. The brass compression ring
securely holds the 1.25" or 2" accessory in place without
marking up its metal barrel.
Dual-Speed Crayford Focuser
The 190mm Mak-Newt features a heavy-duty dual speed
Crayford focuser, designed to handle the weight of your
eyepieces and imaging systems. The Crayford design offers
smooth and gradual motion, free of image shift. If the drawtube slips under the weight of your equipment, simply increase
the focus tension by tightening the focus tension setscrew
(Figure 2).
Crayford focusers generally perform better than rack-and-pinion models because the design eliminates “focus shift”. Focus
shift is when an image moves position in the eyepiece when
it is being focused. This is very hard to eliminate in rack-andpinion focusers due to slight gear and tolerance imperfections
which cause the drawtube to move slightly left or right when
focusing. For the Crayford design, the drawtube is constantly
tensioned (by the focusing shaft and four “roller bearings”)
so the drawtube cannot move perpendicular to the desired
The focuser provides the most focus range for accessories
that require extra in-travel. With a minimum focus height of
58mm, this focuser is an excellent choice for any astro-imag-
Focus tension
set screw
Thumbscrew lock
Focus lock
Figure 2. Use the focus tension setscrew to adjust the weight
capacity of the focuser. Tighten the focus lock thumbscrew to lock
the focuser in place.
ing system. The strong machined aluminum construction supports heavy 2" eyepieces as well as heavy camera bodies.
The smooth focus motion and fine-focus wheel allow precision adjustments for critical focusing of eyepieces and cameras. Once you have reached focus, you can lock the focuser
in place by tightening the focus lock setscrew (Figure 2).
Fine Focus
The focuser features dual speed adjustment with the fine
focus wheel. This small black wheel located on the side of the
right-hand focus wheel allows precise focus adjustment at a
ratio of 10:1, meaning one turn of the focus wheel equals ten
turns of the fine focus wheel.
Use the focus wheels to achieve rough focus on your target
object, then use the fine focus wheel to coax out even more
detail. You’ll be amazed at the amount of detail fine focus
adjustments allow you to view on targets such as the lunar surface, planets, double stars, as well as other celestial objects.
Alternatively, this focuser is also compatible with the Orion
AccuFocus when used with the Dual Speed Bracket (#5049).
Finder Scope Compatibility
The included finder scope dovetail base on the 190mm MakNewt is ready to accept any Orion finder scope.
To insert the finder scope onto your 190mm Mak-Newt, slide
the finder scope bracket into the finder scope dovetail base and
secure it in place by tightening the thumbscrew lock (Figure 3).
Operating the 190mm
Your 190mm Mak-Newt is suitable for both visual use and
imaging. We recommend using high quality eyepieces to
take full advantage of the 190mm Mak-Newt’s optical quality.
For imaging applications, the telescope is optimized for use
Figure 3. Slide the finder scope bracket into the finder scope
dovetail base and secure it in place by tightening the thumbscrew
Figure 4a. Remove the
cover plate on the primary
mirror cell by unthreading the
two thumbscrews that secure it.
Figure 4b. Four tapped
holes are provided for an
optional attachment of a
cooling accelerator fan.
with an APS size sensor, such as the Orion StarShoot™ Pro
or a DSLR camera.
Cooling the Telescope
All optical instruments need time to reach “thermal equil­
ibrium”. The bigger the instrument and the larger the temperature change, the more time is needed. Allow at least 30 minutes for your telescope to cool to the temperature outdoors. In
very cold climates (below freezing), it is essential to store the
telescope as cold as possible. If it has to adjust to more than
a 40°F temperature change, allow at least one hour. You can
use the telescope while it’s cooling down, just note that you
may see “tube currents” which interfere with the telescope’s
ability to resolve a sharp image. Tube currents are essentially heat waves exiting both the optical components (such as
the primary mirror) and the telescope itself. The effect seen
through the eyepiece is much like looking above a hot surface
or fire.
The 190mm Mak-Newt primary mirror cell is compatible with an
optional cooling accelerator fan (available from Orion). Using
the fan significantly decreases the amount of time required for
the telescope to reach thermal equilibrium. Remove the cover
plate on the back of the primary mirror cell (Figures 4a and 4b)
Figure 5. Collimating the optics. (a) When the mirrors are properly aligned, the view down the focuser drawtube should look like this
(b). Here, the secondary mirror is centered under the focuser, but it needs to be adjusted (tilted) so that the entire primary mirror is visible
(c). The secondary mirror is correctly aligned, but the primary mirror still needs adjustment. When the primary mirror is correctly aligned,
the “dot” will be centered, as in (d).
to gain access to the threaded holes for the cooling accelerator fan attachment.
Connecting the 190mm Mak-Newt to a Mount
The 190mm Mak-Newt requires a pair of tube rings and a
dovetail mounting plate compatible with large Orion mounts,
such as the Sirius or Atlas EQ-G. The optical tube is compatible with 235mm I.D. tube rings (available from Orion).
Balancing the 190mm Mak-Newt can be achieved by sliding
the dovetail mounting plate forward or backward within the
mount’s dovetail holder. You can also move the telescope forward or backward within the tube rings. The tube rings offer
the most adjustment range. Loosen the tube ring clamps
slightly and slide the telescope tube forward or backward as
needed to reach optimum balance, then retighten the tube
ring clamps. Rotating the telescope to achieve a comfortable
eyepiece angle is done in the same fashion. Simply loosen the
tube ring camps just enough to allow the optical tube to rotate
within the tube rings. Tighten the tube ring clamps securely
once you have reached the desired eyepiece orientation.
Imaging with the 190mm Mak-Newt
The Premium 190mm Maksutov-Newtonian Astrograph is
ideal for just about any imaging camera, from small webcam
or planetary imagers, to DSLRs and large CCD cameras. The
Maksutov-Newtonian optics reduce the coma and field curvature, which allows you to utilize the entire imaging area of
your camera without the need to crop the edges of your astroimages.
Imaging equipment is often much heavier than an eyepiece.
The Crayford focuser is capable of handling the weight of your
CCD or DSLR camera. Adding tension to the focuser drawtube
(Figure 2) will increase the amount of weight the focuser can
handle. Install your camera onto the supplied camera adapter
on the focuser during the day. Check the focuser for any slippage. If the focuser drawtube slides under the weight of the
camera, you will need to add more tension to the focuser.
Using a DSLR Camera
To attach a DSLR camera, all you will need is the appropriate T-ring for the make and model of your camera, and the
supplied camera adapter. Simply attach the T-ring to the camera body and thread the 2" prime focus camera adapter into
the T-ring. Insert the barrel of the camera adapter into the
focuser’s 2" eyepiece holder and secure it with the eyepiece
Using a CCD Imager
Most CCD imagers will have a 1.25" or 2" barrel ready to
attach directly to your telescope like an eyepiece. No adapter
is required. Simply insert the barrel of the CCD camera into
the 1.25" or 2" eyepiece holder and secure the camera with
the silver thumbscrew lock.
Collimating the Optics
(Aligning the Mirrors)
Collimating is the process of adjusting the mirrors so they are
aligned with one another. Your telescope’s optics were aligned
at the factory, and should not need much adjustment unless
the telescope is handled roughly. Accurate mirror alignment is
important to ensure the peak performance of your telescope,
retaining ring
Metal cap
Figure 7. Loosen the knurled retaining ring on the secondary
mirror holder to allow the secondary mirror holder to rotate.
Figure 6. Unthread the metal cap that covers the secondary
mirror collimation screws.
so it should be checked regularly. Collimating is a relatively
easy process and can be done in daylight.
To check collimation, remove the eyepiece and look down the
focuser drawtube. You should see the secondary mirror centered in the drawtube, as well as the reflection of the primary
mirror centered in the secondary mirror, and the reflection of
the secondary mirror (and your eye) centered in the reflection
of the primary mirror, as in Figure 5a. If anything is off-center,
proceed with the following collimating procedure.
The Collimation Cap and Mirror Center Mark
Your 190mm Mak-Newt comes with a collimation cap. This is
a simple cap that fits on the focuser drawtube like a dust cap,
but has a hole in the center and a silver bottom. This helps
center your eye so that collimating is easy to perform. Figures
5b through 5d assume you have the collimation cap in place.
In addition to providing the collimation cap, you’ll notice a tiny
ring (sticker) in the exact center of the primary mirror. This
“center mark” allows you to achieve a very precise collimation of the primary mirror; you don’t have to guess where the
center of the mirror is. You simply adjust the mirror position
(described below) until the reflection of the hole in the collimation cap is centered inside the ring.
NOTE: The center ring sticker need not ever be removed
from the primary mirror. Because it lies directly in the
shadow of the secondary mirror, its presence in no way
adversely affects the optical performance of the telescope or the image quality. That might seem counterintuitive, but it’s true!
Aligning the Secondary Mirror
With the collimation cap in place, look through the hole in the
cap at the secondary (diagonal) mirror. Ignore the reflections
for the time being. The secondary mirror itself should be centered in the focuser drawtube, in the direction parallel to the
length of the telescope. The secondary mirror should face the
focuser. If the mirror appears to be tilted away from the fo-
mirror alignment
Figure 8. Use a Phillips head screw driver to make adjustments
to the three secondary mirror alignment setscrews.
cuser, the mirror rotation will need to be adjusted. Typically,
this adjustment will rarely, if ever, need to be done. It helps to
adjust the secondary mirror rotation in a brightly lit room with
the telescope pointed toward a bright surface, such as white
paper or wall.
To adjust the secondary mirror rotation:
1. Remove the metal cap that covers the secondary mirror
collimation screws by carefully unthreading it (Figure 6).
Be careful not to touch the corrector glass.
2. Loosen the knurled retaining ring on the secondary mirror
holder (Figure 7) about ¼ turn, or enough to free the tension in the ring.
3. Carefully grab the inside of the secondary mirror holder
with your thumb and index finder and rotate the secondary mirror holder as needed so that the secondary mirror
faces the focuser.
4. Retighten the knurled retaining ring and make sure it does
not cause the secondary mirror to shift or rotate.
The tilt of the secondary mirror may very occasionally require
adjustment. If the entire primary mirror reflection is not visible
in the secondary mirror when using the collimation cap, as in
Figure 5c, you will need to adjust the tilt of the secondary mirror. Using a Phillips head screwdriver, loosen one of the three
alignment setscrews while tightening the other two (Figure 8).
Figure 9. The
tilt of the primary
mirror is adjusted
with three pairs
of collimation
Primary collimation
adjustment screws
Out of collimation
Figure 10. A star test will determine if a telescope’s optics are
properly collimated. An unfocused view of a bright star through
the eyepiece should appear as illustrated on right if optics are
perfectly collimated. If circle is unsymmetrical, as in illustration on
left, scope needs collimation.
Do not loosen the center screw. The goal is to center the primary mirror reflection in the secondary mirror, as in Figure
5d. Don’t worry that the reflection of the secondary mirror (the
smallest circle, with the collimation cap “dot” in the center) is
off-center, since that adjustment is made when aligning the
primary mirror in the next step
Aligning the Primary Mirror
The final adjustment is made to the primary mirror. It will need
adjustment if, as in Figure 5d, the secondary mirror is centered under the focuser and the reflection of the primary mirror is centered in the secondary mirror, but the small reflection
of the secondary mirror (with the “dot” of the collimation cap)
is off-center.
The tilt of the primary mirror is adjusted with three pairs of
collimation screws (Figure 9). The collimation screws can be
turned with a Phillips head screwdriver and a 2.5mm hex key.
Each pair of collimation screws work together to adjust the tilt
of the primary mirror. The allen-head screw pushes the mirror forward while the Phillips head screw pulls the mirror cell
back. One must be loosened and the other tightened by the
same amount in order to adjust the tilt.
To adjust the primary mirror tilt:
1. Tighten and loosen one of the pairs of collimation screws
by one turn.
2. Look into the focuser using the collimation cap and see if
the secondary mirror reflection has moved closer to the
center of the primary. You can tell this easily with the collimation cap and mirror center mark by simply watching
to see of the “dot” of the collimation cap is moving closer
or farther away from the ring on the center of the primary
3. Repeat this process on the other two pairs of collimation
screws, if necessary. It will take a little trial and error to get
a feel for how to adjust the mirror to center the “dot” of the
collimation cap in the ring of the mirror mark.
When you have the dot centered as much as possible in the
ring, your primary mirror is collimated. The view through the
collimation cap should resemble Figure 5d. Make sure all
the collimation screws are tight (but do not over tighten), to
secure the mirror tilt. A simple star test will indicate how well
the telescope optics are collimated.
Star-Testing the Telescope
When it is dark, point the telescope at a bright star and accurately center it in the eyepiece’s field of view. Slowly de-focus
the image with the focusing knob. If the telescope is correctly collimated, the expanding disk should be a perfect circle
(Figure 10). If the image is unsymmetrical, the scope is out
of collimation. The dark shadow cast by the secondary mirror
should appear in the very center of the out-of-focus circle, like
the hole in a donut. If the “hole” appears off-center, the telescope is out of collimation.
If you try the star test and the bright star you have selected is
not accurately centered in the eyepiece, the optics will always
appear out of collimation, even though they may be perfectly
aligned. It is critical to keep the star centered, so over time you
will need to make slight corrections to the telescope’s position in order to account for the sky’s apparent motion. Point
the telescope at Polaris (the north star) if you do not have a
mount that tracks.
Lateral Support System
One of the exciting new features of this telescope is lateral
support screws to secure the position of both the primary mirror and corrector plate which will further stabilize the optics.
These screws are visible around the perimeter of the tube on
both front and back (Figures 11a and 11b) and have been
set at the factory. The Phillips-head screws pictured in Figure
11b are cover screws. The Lateral Support screws can be
accessed by adjusting these screws (Figure 11c). No adjustment of this component is necessary when performing routine
collimation. If larger adjustments do need to be made simply
loosen these support screws slightly. When finished re-tighten
just tight enough that you feel the slightest resistance when
tightening. Do not over-tighten these screws as pinchedoptics or other distortions could result.
Care & Maintenance
Give your telescope reasonable care and it will last a lifetime.
When not in use, keep its dust cover on as well as the dust
Figure 11a. The corrector
plate Lateral support
adjustment screws (one of
three shown).
Figure 11b. The primary
mirror Lateral support cover
screw (two of three shown).
Figure 11c. Detail of the
primary mirror Lateral support
adjustment screw (one of three
cap on the eyepiece opening. Keep the telescope inside the
hard storage carrying case when not in use. Store it indoors
or in a dry garage. Do not leave the telescope outside except
when using it. The optical tube is aluminum and has a smooth
anodized surface that should resist scratches and smudges.
If a scratch does appear on the tube, it will not harm the telescope. Smudges on the tube can be wiped off with standard
household cleaners such as Windex or Formula 409.
The 190mm Mak-Newt’s corrector lens is exposed at the front
of the telescope. Without using a dew shield and/or heated
dew zapper (available from Orion), dew can easily form on the
corrector glass. We recommend using the Orion Dew Zapper
Pro™ with the medium aperture heating band (made for 6-8"
telescopes) to completely prevent dew from forming on the
corrector glass.
When you are ready to pack up your telescope at the end
of the night, avoid immediately storing it if you encountered
heavy dew and the telescope is damp. Instead, bring the telescope inside and allow the moisture on the telescope to evaporate. If dew forms on the inside or outside of the corrector
lens, then leave the dust cover off of the telescope until all the
moisture has evaporated. Once the telescope has completely
dried out, place the dust cap on the telescope and store it in
a dry location.
Cleaning Optical Surfaces
In general, your telescope will only need to be cleaned on
a very minimal basis. Dust particles on the corrector lens
will not affect the optical quality of your 190mm Mak-Newt.
Fortunately, because the 190mm Mak-Newt is a closed tube
design, the primary and secondary mirrors will barely accumulate any dust (if dust caps are kept on during storage). Loose
dust can simply be blown off with air, using a compressed air
can or blower bulb (available from Orion). Any remaining dust
is best left alone, unless the build up is extreme. Finger prints
and water marks should be cleaned from your telescope’s
corrector lens. Any quality optical lens tissue and cleaning
fluid specifically designed for multi-coated optics can be used
to clean the telescope’s corrector lens as well as the lenses
of the eyepieces and finder scope. Never use regular glass
cleaner or cleaning fluid designed for eyeglasses. Before
cleaning with fluid and tissue, however, blow any loose particles off the lens with a blower bulb or compressed air, or
lightly brush the lens with a soft camel hair brush. Apply some
cleaning fluid to a tissue, never directly on the optics. Wipe the
lens gently in a circular motion, then remove any excess fluid
with a fresh lens tissue. Oily fingerprints and smudges may
be removed using this method. Use caution; rubbing too hard
may scratch the lens! Clean only a small area at a time, using
a fresh lens tissue on each area. Never reuse tissues.
Premium 190mm (7.5") f/5.3
Maksutov-Newtonian Astrograph
Optical configuration: Maksutov-Newtonian
190mm (7.5")
Focal length:
1000mm (39.37")
Focal ratio:
mirror minor axis:
5 knife-edge baffles
Machined aluminum dual-speed
(10:1) Crayford, accepts 1.25" or 2"
accessories, brass compression ring
Drawtube travel:
Primary mirror:
Low thermal expansion glass
Mirror coatings:
Enhanced aluminum (94%) with
SiO2 overcoat
corrector lens:BK-7 Schott glass, fully multi‑coated
Lens cell:
Machined aluminum
Optical tube:
Seamless aluminum
Outside diameter:
235mm (9.25")
10 kg (22 lbs.)
95.25cm (37.5")
One-Year Limited Warranty
The Orion Premium 190mm f/5.3 Maksutov-Newtonion Astrograph is warranted against defects in materials or workmanship for a period of one year from the date of purchase. This warranty is for the benefit of
the original retail purchaser only. During this warranty period Orion Telescopes & Binoculars will repair or
replace, at Orion’s option, any warranted instrument that proves to be defective, provided it is returned
postage paid to: Orion Warranty Repair, 89 Hangar Way, Watsonville, CA 95076. Proof of purchase (such
as a copy of the original receipt) is required.
This warranty does not apply if, in Orion’s judgment, the instrument has been abused, mishandled, or
modified, nor does it apply to normal wear and tear. This warranty gives you specific legal rights, and you
may also have other rights, which vary from state to state. For further warranty service information, contact: Orion Customer Service (800) 676-1343; support@telescope.com.
Orion Telescopes & Binoculars
89 Hangar Way, Watsonville CA 95076
Customer Support Help Line (800) 676-1343 • Day or Evening
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