Flash Photography: The Best of Q&A Lesson 1
Questions from previous sessions you may find informative
FLASH METERING
Q: Is there a metering mode (Canon 5D) that you use more than others?
A: I usually just leave my camera set to matrix mode. I never use spot metering because that can cause some problems.
It is best to use a metering mode that analyzes the entire scene rather than spot metering which meters only a narrow
area. Fortunately the metering does not have to be perfect because we have the histogram to fine tune and make perfect
exposures.
Q: I've been going back over Lesson 1 again and want to be sure I understand the concepts. In some of your
sample shots, you said the shutter speed was too slow and you should have used a tripod. Also, Lesson 1 said
shutter speed is important and we should choose one that keeps the photo from being blurred. Since the shutter
speed only controls the background, does that mean that the flash freezes the action of the main subject and I
don't have to worry about too low a shutter speed unless I'm concerned about the background blurring? For
instance, when I'm trying one of those paparazzi shots, would I put the camera on Aperture priority and not worry
about what shutter speed is selected? Or could I use Manual and fire away, even if the manual exposure
suggests I'm under or over exposed (assuming I don't care about the background)? It sounds like the flash
duration is so short that it would freeze the subject, even if it moved, so I'm wondering if I should concern myself
with shutter speed only when I want the background sharp, too.
A: Shutter Speed controls how fast or long the shutter is open. As you know when it is really fast it can freeze a bird in
flight. When it is slower the bird will be blurry. That is how it works regardless of flash or not.
Now to take that further; if that bird is flying by at dusk when the light level drops it will almost be guaranteed to be blurry
because you cannot (theoretically) get a fast enough shutter speed to freeze the bird in flight when light is really low. (You
can if you increase ISO VERY high but that is not a great solution). So you add flash and its instant burst of light freezes
the bird in flight instead of the shutter speed.
Let's say hypothetically that at the dusk brightness level your aperture is f/2.8 (your widest) and the new S.S. for that light
level at ISO 200 is 1/8. The bird is blurred so you put on the flash and the bird is now frozen in flight by the flash, but the
S.S. is still long so that made the trees in back blur left to right because you were panning with the bird as it flew by. I
hope that makes sense.
The shutter controls ambient light even though we often refer to it as controlling the background. If there is lots of ambient
light on the subject and the garden in the background, changing the S.S. changes the light on the subject and the garden
at the same time.
In answer to your points: Regarding the image I wished I had a tripod is probably the person hiking in the woods and you
can see they are blurry due to moving and also my hand holding. A tripod would have helped some in regards to the hand
holding. Choosing a faster shutter speed to keep the photo from being blurred also helps. This is the simple part: if your
shutter speed is long or slow then the kid on the trampoline might be blurry jumping up and down, so a faster S.S. helps
prevent that blurring.
If you have a moving subject that is blurring, the flash will freeze them in position and if the camera is on a tripod at that
time the background will not blur. But if you are hand holding and panning left to right following a runner, the background
and runner will blur if you pan using a long s.s. The runner will have some blurriness as well. Turn on the flash and pan
with the runner and the flash will freeze the runner in position while the background, not getting any flash, will blur as you
move the camera. (This is in a later lesson)
For paparazzi, it might be cool if the background blurs some as long as the flash clearly shows the subject. You can also
ignore your meter and choose a fast S.S. to prevent that blurring and that will also darken and prevent the background
from showing up in the picture. If you choose AP then the shutter could be long depending on the brightness. So it could
blur and a lot if it’s dark outside. Or just pick a faster S.S. ignoring the meter.
Now here is the trick I use. I am taking pics and the meter says 1/4 second S.S. for the brightness level at ISO 100. I
increase ISO to 200 and am now at 1/8 s.s. That is what the meter suggests for the properly exposed background. But
let’s say we want detail back there and don’t care about the background being perfectly exposed. So I change my S.S. to
1/30, that's minus -2 from what the meter suggest and I shoot away. The background still has nice detail of some stuff like
lights, but it is dark. The new S.S. of 1/30 prevents blurring on most subjects. So I am manually overriding the meter,
preventing blurring, and have some detail in back.
Q: Janice's question made me realize that I'm confused between "shutter has no effect of flash
exposure" and "sync speed as it refers to timing and the synchronization of the shutter and flash
occurring together". Can you elaborate...one minute I get it and the next I'm confused. Also, it's my
understanding that I can set the sync speed which, in my case is 250 or lower. Or do I always set it at
250?
A: You do not have to set it to 1/250; you set it to what the meter says will provide a good ambient exposure. When the
flash is on in this case it will meter the flash exposure/output independently.
So here is my explanation to understand this. You go outside at night (pitch dark) with your camera on tripod and set it up.
You have someone sit 10' in front of the camera. You set you camera at 1/250, turn on the flash, and take a picture of the
person. You have a picture of the person flashed by the flash and a pitch black background. Now you set your shutter
speed to 1 second and take another picture. You have the same picture as before; a flashed person with a pitch black
background. These two pictures prove that S.S. has no affect; both have a black background despite a very different
shutter speed.
Now do the same test at dusk when there is still plenty of light. Take one pic at 1/250 and the background is black.
Change the S.S. to whatever the meter says for proper ambient exposure, and let’s say it is 1/4 second, and take another
pic. You now have an exposure with a great background. Both pictures have normal flash exposure while one has a black
background and the other has a normal background. Shutter speed had no effect on flash exposure.
One other thought here that may help: the sun, a lamp in the living room, a flashlight, a ceiling light in a store; are all
continuous light. They are on all the time and you may use any of them to take a picture because we need light to
photograph. These lights sources are controlled by aperture and/or shutter speed. Change one or the other and the
exposure changes.
Then you have flash. It is not continuous. It is not on all the time, it flashes in an instant, like 1/800th second, and then it is
off while your shutter is still open to capture the ambient light.
So think about that instant flash of light. It happens faster than we can blink. Your shutter is open for a certain amount of
time that you set on the camera. If it is open for 1/60 the flash fires instantly while the shutter is open. Go into that dark
room and the S.S. is now 2 seconds. The flash fires and again, it flash duration is instant while the shutter is open for 2
seconds. So changes to the S.S. don’t affect flash because the flash is instant and has the same duration each time and
happens really fast when the shutter is open.
Q: When you talk about using the autofocus point to get proper flash exposure - If I have a black tuxedo and a
white dress, does it make a difference what I focus on? Is the flash output based on distance, or on whether the
flash thinks there is enough light for proper exposure (black vs. white, etc.)?
A: Yes, black or white will affect the flash exposure. When it sees black then it will over flash to some extent and with
white, under-flash. If you can get one AF point on the face in this case then that would be better. The flash exposure is
based on distance AND when it knows it sent enough flash output for proper exposure
Q: I'm never sure whether I should be using spot metering, evaluative, center weighted, etc. If I'm shooting
outside and using fill flash, I know that I should meter for the background ambient light, and use the flash for fill.
But what if the background has bright sky and dark trees? It seems like either the sky is blown out, or the trees
look black. I'm never quite sure where I should be metering, and what mode I should use. And I was thinking
more of when I have a bride and groom outdoors and they're squinting into the sun. Then I'll put them in the
shade, which can be very dark. I'm trying to balance the ambient light, and this can be a challenge!
A: Your camera should indicate right on the top LCD what metering mode you are in. NEVER spot, use matrix instead.
When you are in contrasty light like you describe, you don’t have a lot of options, so you pick one over the other.
BUT...you really don’t care about sky or trees; rather what exposure is best for the people. I meter off the people and set
that exposure. If they are totally in shade and you can minimize areas that are in sun that should work. You just adjust
your ambient exposure for the darker areas and use flash as fill.
SHADOWS CREATED BY FLASH
Q: When I reviewed the pictures in my computer I realized many of them have a shadow.
I was able to take a good one, but more by luck, than because I knew what to do.
How can I avoid the shadow when using flash?
A: That shadow...everybody hates that shadow and so do I. But it is a reality of flash on camera. When you
have any light pointed at a subject the direction of the shadow created by that light falls off behind the
subject in the opposite direction of the main source. The best approaches to getting rid of the shadow
created by on-camera flash is to have the background right behind the subject as that minimizes the size of
the shadow. Or have the subject so far from the background that the shadow disappears behind them. But if
your subject is 5-10' in front of the background you have a big shadow and there is not much you can do
about it with direct on-camera flash unless you bounce the flash off the ceiling which weakens and softens
the flash.
WATCHING THE VIDEOS
Q: This is a computer problem. I have a Mac, running OS 10.6.6. I have QuickTime Player 7.6.6 (pro). I can't see
any of the videos that are posted in the lessons. The screen in Safari just opens up black. I also tried Firefox.
Then, I tried to paste the URL into the player. It says the address is wrong. Help! What do I need to do to be able
to see the videos?
A: I came up with an odd but workable solution. After hours of Googling, I decided to download the Windows Media
Components for QuickTime by Flip4Mac. (Free) Then, I tried opening the Windows Media versions of your files, in Safari,
on my Mac, and they work!!! Hurrah! Now, it's time to watch and catch up with my reading. You might suggest this to other
people with this problem.
NIKON TTL-BL
Q: For the Nikon SB-900, the mode TTL BL (Automatic Fill Flash is not mentioned). Can you give me your
thoughts on it because, in his book, Mike Hagen suggests using this mode rather than TTL without the BL. What
are your thoughts on the subject? The following might help you in answering my question. Here's what Mike has
to say: "TTL BL works to balance the light between the background and the subject. TTL without the BL is similar
to Nikon's older flash mode which only puts out enough light for the subject. In other words, regular TTL doesn't
try as hard to balance the flash with the background." I'm wondering if this is the mode I should then use for the
assignments.
A: I think what you have mentioned is certainly true. I am a Canon photographer so I have not been able to put my hands
on a Nikon and test some of the features that continue to evolve. I have however, heard just what you mention here and
what Mike states, that the BL feature (which originally meant Back Lit, but now is Balanced Fill) is a more accurate flash
fill option. Most of the time the cameras metering and the flash metering are separate but with TTL BL the two metering
methods work together fro more accuracy. As these two metering systems work together, the flash metering becomes
heavily center weighted and that calculation is compared to the camera metering of the ambient area to produced a better
balance between ambient and flash.
Q: TTL BL (Automatic Balanced Fill Flash), works to balance the light between the background and the subject.
TTL (without the BL) is similar to Nikon's older flash mode which only puts out enough light for the subject. In
other words, regular TTL doesn't try as hard to balance the flash with the background. TTL uses the camera's
light meter to figure out how much energy is dumped from the capacitor and how much is needed to expose the
subject at medium brightness (18 grey). In TTL terms, this is called o.o. When you are in TTL mode, you can
change the amount of energy your flash will output. For example, if you dial in +1.0, then your flash will put out
one stop more power than 0.0. TTL BL's goal is to balance the ambient light (background) with the subject
(foreground). I believe that TTL-BL is not available in spot metering because spot metering does not consider the
background...only subject is considered then. TTL-BL attempts to balance the background with the subject...as
stated above. TTLs' purpose is to expose only for the subject and NOT for the background light. So, to me it
makes sense that when changing the metering to spot, only TTL mode becomes available.
A: You are absolutely correct. TTL-BL is an available OPTION if both spot metering and FV lock are NOT used. Camera
must be in either matrix or center weighted modes in order for your flash to be able to go into TTL-BL. The camera mode
has nothing to do with the TTL-BL option...the word "option" is the answer to it all, I think.
SLOW SYNC MODE
Q: I have a question for the first part of the assignment. I use a Nikon D3 - do I have to set it a slow-sync flash
mode to do this?
A: Av mode will work like P mode if you do not engage Slow Sync Mode. I recommend that you do engage it and then
when you do not want long shutter speeds in low light situations you use P mode instead of Av
Q: As I understand, slow sync mode is selected in camera. The sentence where you state: To set the SB800 to
SLOW SYNC MODE, go to the mode dial on top of the camera and select, etc... So, are you saying that by setting
slow sync mode in camera that the flash unit then automatically syncs with setting in camera?
A: The way Av works is without using Slow Sync Mode the camera acts like Program with a shutter speed range limited
between 1/60 - 1/250. I still to this day don’t get why they did that but they did. When you select Av mode you want the
camera to pick the best shutter speed for proper background exposure. If you want to shoot the party and want your S.S.
between 1/60 and 1/250, then you pick Program mode.
But if you want true AV mode on a Nikon you must set the camera to Slow Sync Mode and then it is a true Aperture
Priority setting.
No matter whether you are in AV mode of Program mode, the flash is always synced with the camera and the metering
works together with camera for proper flash exposure. The modes that we are talking about relate to how the camera
meters and applies shutter speed.
Q: OK, I thought I understood this, but couldn't find my ‘slow sync mode’ setting, which I knew I had seen before,
so I set my camera (Nikon D200) on Rear sync - later I read in my camera manual that the slow sync doesn't work
in Manual mode, so effectively I didn't really have it set on slow sync, that's probably why I didn't see it. I try to
take my photos in Manual for better control if possible, so I took most of my couple photos last night with
manual. What is really happening if I set it in rear shutter sync and the camera is in manual? And the flash is TTL
(SB800). In the MENU of my camera I found a menu item under Flash Shutter speed, where I could set my shutter
speed to all sorts of things - down to 30 seconds. Now, when you are doing low light, flash photography like
assignment one (lesson one) should you use these settings? I have mine set at 1/30s, just because I am
comfortable with that, but should I have set it at something longer because I was doing the dusk thing?
A: When you are in manual camera mode and choose 1/2 second shutter speed you are in essence using slow sync, you
just set it manually. You are basically doing the same thing. It is when you are in Av or P mode that has that limit at 1/60
where selecting slow sync mode allows the camera to over ride the main settings and choose a slow S.S. when needed.
If you shoot mostly in manual you will never need to engage Slow Sync mode.
As far as menu settings, I usually don’t mess with those menu items that relate to S.S. because I can do everything with
what is available on the outside of the camera so to speak. Once you reset a menu item sometimes and it does a certain
thing and you forget you changed it and then begin having problems, remembering you changed the menu item might
take a bit and that causes frustration. As you mention; "you can get your s.s. to do all sorts of things. “ You can do that
manually or in an automated mode without changing the menu item.
CAMERA SHOOTING MODES
Q: For the last couple of years, I've been following PPSOP courses and most of them tell me: use the manual
mode. Now it is the first course where we spend so much time talking about the other modes. So at the end, I am
confused, should I use other modes again? Looks like it is quite dependent on the context. Should I keep
shooting in manual in all cases?
A: Manual mode is still a great mode and the reason I spend so much time on the different modes is to understand how
each one works with flash. They all work a bit different with flash. Like P mode has a 1/60 - 1/250 limit on shutter speeds
while Av mode has all shutter speeds available (Nikon requires slow sync mode) and Sp is best when Shutter Speeds are
more important like action subjects. So manual is still the best to master but I think you will want to understand the
limitations of the other modes as well in case you wish to use them with flash.
SHUTTER SPEED AND F/STOPS
Q: When I have my camera in manual mode, I see that my F stop is F/11 and I should set my shutter speed to go
with it, let's say (like your example) it looks like (at ISO 200), it should be a shutter speed of /100 s. Then I tried to
changed aperture only, ISO 200, F/8, same shutter speed. Yes, I can see the difference, F/8 allowing more light to
come in (background overexposed). But when I took that second photo, changing the aperture to F/8, my meter
on my camera said that my shutter speed should be 1/200s. So for the next attempt, I set it all manually and used
what the meter read. Do you mean that we should follow the meter reading exactly, even though you state
"Shutter speed does NOT control flash exposure while F/stop does." Or do you mean let the flash light it and
ignore the meter. Because to my eye, adjusting the shutter speed to match what the meter says (In this photo)
looks better.
A: Here is an example, and you may want to try this test yourself. You are indoors and it is dark inside and when you look
at your meter it says 1 second at f/11. That is too long to hand hold. You turn on the flash and take a picture at 1/60 at f/11
and it is perfect. This shows you that you have two lights sources: flash and ambient and because it was dark you
abandoned the ambient light for your picture and used flash instead and got a great pic.
So the answer to your question is no, you do not always follow the meter. Instead you have the option to do a couple
things; use flash or ambient or flash and ambient. In your examples you are shooting manually, figuring this out yourself
and not letting the camera do everything and that is good. By changing your f/stop to 8 and following that by changing
your S.S. to 1/200 you override the cameras recommendation and that is fine because it allows you to determine how you
want the picture to look.
Here is a test similar to what you are doing. Set that flower pot in the shade on the edge of your patio like on a chair and
point the camera at the pot and manual meter mode. Take a pic at the meter setting with no flash. The pot is probably
close to silhouette. Now turn on the flash and take another and the background should look quite good and the pot is
nicely flashed. Let’s say your exposure combo is f/11 at 1/100 like you already had. Change your f/stop to 16 and the S.S.
is now 1/50. Take another pic and it should look just like the one before-proper exposure everywhere. Next take one at
1/100 and one at 1/200 and leave the f/stop as it is.
The results should be that the background keeps getting darker while the pot stays much the same. It might appear to get
darker but that is because the ambient light is not lighting the pot as you reduce ambient light (changing to faster S.S.)
making it appear darker. You used the shutter speed to control the ambient background light but did not change the flash
exposure so the pot stays the same while the background got darker.
Q: During shooting individuals and groups in preparation for a photo journal, I made a very amateurish mistake.
Shooting the individuals with aperture priority, f3.2, ISO 500, SB900 set on iTTL with diffuser, spot metering,
mounted on camera, indoors with some fluorescent ambient light, I enjoyed reasonably good results at a shutter
speed of 1/40 to 1/50 (a little slow, I know). In grouping the individuals for the group shots, however, I had to
increase the DOF by changing the aperture to f6.3. When I did this I was guilty of a beginner's mistake by not
checking the shutter speed. Although flashed properly, my group shots suffered from camera shake as I was
doing this handheld. My question is, since the flash is much faster than even high shutter speeds, under what
conditions can you expect the flash to "freeze" the subject even at lower shutter speeds? I typically use a manual
setting for such activities with a couple of test flashes for each setting to confirm exposure with good results. I
did not do that this time.
A: The flash always freezes the subject. It is what you do with the shutter speed that gives you the illusion that flash did
not freeze the subject. The longer the S.S. (a shutter speed) the more blur of the background/ambient light part of the
exposure. That blur is along the edges of your subject where flash light meets ambient light, such as the edge of the body
of the person. As the shutter is open during a slower S.S. and the camera is jiggling from hand holding the only light still
on is the ambient light since the flash is done flashing. This jiggling blurs the ambient light and it then overlaps the sharp
edge the flash created on the subject and starts to overlap that sharper area and blur it out.
Unfortunately there is no button to use that fixes this, so you have to do this manually.
The solution is a faster S.S. Indoors and using AP mode is dangerous as you have just experienced. The dark interior
forces the camera to choose such a long S.S. that you have the problems you just had. The S.S. minimum is 1/50 to 1/60
but I have often used 1/30 and held my breath when shooting and asked all people to hold still. This was more in the film
days when you had one set ISO-the speed of film in your camera. With digital we can change ISO for faster shutter
speeds, but noise is always an issue.
So here is my solution for these event issues: AP mode is just fine for outside unless it is night time, then the problems
can be the same. I go into the location and let’s say it is the afternoon and there is a church event. Before I ever turn on
the flash I determine my S.S. exposure. I point the camera around watching the meter and what it suggests for an s.s. If
there are a lot of windows then you have more light and probably not have a problem with s.s. But since this analogy is
about having a problem, then I will create a problem. There are no windows and its dark!! 
So I move my camera around doing an evaluation of the ambient light. I specifically make sure my metering check
includes the average part of the room with any lights that might be on the wall and so on. At ISO 100 where I always start,
I am getting a recommended exposure for example of f/4 at 1/4 second. Too slow S.S. as we know. So the first thing I do
is switch to manual mode and set f/4 at 1/4 as the starting point, then I purposely underexpose the ambient light exposure
by -2 stops and that means changing the s.s. to 1/15. Still to slow on the S.S. for hand holding but it’s the point here that is
important:
-If you under expose the background -2 you often still have detail there, especially when you have lights on the wall
like a hotel ballroom. These add background detail and that helps your picture over a pitch black background. We all
know how to create black backgrounds in low light areas. It's called P mode! But when you just underexpose the
background to gain faster S.S. you maintain your visual depth. That's the key.
So the strategy is to meter the scene and determine where your S.S. is going to be and pick an aperture that is not quite
wide open. In this example we started at f/4 at 1/4 second, then over rid the suggested S.S. and purposely chose an S.S.
that is -2 from meter reading.
Now we are at f/4 at 1/15 second at ISO 100. Next increase ISO to 400 and the S.S. is now 1/60. So if you now need to
be at f/6.3 then you increase your ISO to around 1000. Or pick a shutter speed that allows you to stay with a lower ISO.
Just be sure you hold the camera very still if you are below 1/60 for some shots. I have done it this way many times and it
works. Select settings that allow hand holding and an exposure that keeps just enough detail in your picture to avoid pure
black and have some detail. You should try this at home to master it.
GUIDE NUMBERS
Q: You mentioned guide number several times, but I am not sure what they are. Can you give a brief explanation?
A: There is a formula in lesson 1 that describes this and what it is, is simple math. The higher the GN, the more powerful
the flash! GN is created by distance to subject and aperture. So if your subject is 10' from the camera and at full flash
output requires f/20 then you have a flash with a GN of 200. That is roughly a Canon 580EXII. You can also use GN to
establish the f/stop to use. If your subject is 15' from camera and you know that your flash is GN200, then 200 divided by
15' is f/13. That's pretty much it. GN is an indication of how much power or output the flash unit has.
NOISE
Q: I have the D200 and am noticing with a slower shutter speed and ISO 640, I have a lot of noise. Is it the
camera? I think that ISO 640 should still be okay, but perhaps it is the combo of slow shutter speed WITH the
higher ISO? Just noticing this on the flash photos I've been doing this week.
A: Both the low light level and high ISO can cause noise for sure. In bright sunny scenes the light level is high in
comparison to the noise level of the sensor. In low light scene the light level is closer to the noise level of the sensor and
is thus amplified causing it to be more obvious. The best choice is to turn on any noise reduction options in camera first
for really long exposures and then use more noise reduction in Photoshop or a noise reduction program like Noise Ninja.
FLASH TO SUBJECT DISTANCE
Q: In this lesson you talk about focal length from your subject. In certain cases you have a wide range. Yet in
certain areas you have a set distance like 10' or 20'that you must be in order to get a correct flash exposure. I'm
not very good with knowing how far away I am from my subject just by looking at it. So how do I know?
A: You don’t have to be any particular distance for proper flash exposure because the measurement is automatic by the
flash and camera. At 10' or 20' the flash should output the proper amount of flash for a correct exposure. There are of
course distances where the flash can no longer reach because the distance is too great, but there are ways even to adapt
to that. Open your aperture wider and the flash reaches further. Increase your ISO and the flash range goes further. So
really you can use your flash anywhere within its ranges for proper flash exposure