03: Flash sync Av Mode (Quote Chuck Westfall)

[dpanicc1]

According to Chuck Westfall:

"03: Flash sync
speed in Av
mode
0: Auto
1: 1/200 sec. (fixed)

Use option 0 for fill-flash in low light. Option 1 works well for
wedding candids in low light.
Side note: Option 1 shuts off the camera's exposure meter,
and can cause massive overexposure if used in bright
daylight. Be Careful!"

Can anyone elaborate on, specifically, this statement: "Use option 0 for fill-flash in low light. Option 1 works well for wedding candids in low light."

What option do you use and why.

Thanks,
Dan

[DAMphyne]

Option '0' tries to match the pre-set aperature with a shutter speed with-out-flash, it then tells the flash to "blend" with the ambient scene.
Option '1' pre-sets the shutter to 1/200 sec, then tells the flash to properly expose the scene with the aperature that is also pre-set. This is the way the old, auto-exposure, flashes worked.
The reason that '0' works well in outdoor fill use is that your shutter speed is normally above 1/60 sec, so you don't get movement in the backgroundor by the subject(ghosting).
Indoors, with low-ambient light, a slow shutter-speed can cause just these effects, which is not usually wanted.
You can always adjust exposure with option '1' by using the (+ or -)setting.

[Tom W]

Option '0' tries to match the pre-set aperature with a shutter speed with-out-flash, it then tells the flash to "blend" with the ambient scene.
Option '1' pre-sets the shutter to 1/200 sec, then tells the flash to properly expose the scene with the aperature that is also pre-set. This is the way the old, auto-exposure, flashes worked.
The reason that '0' works well in outdoor fill use is that your shutter speed is normally above 1/60 sec, so you don't get movement in the backgroundor by the subject(ghosting).
Indoors, with low-ambient light, a slow shutter-speed can cause just these effects, which is not usually wanted.
You can always adjust exposure with option '1' by using the (+ or -)setting.

What you say is absolutely correct and I have a few pictures to prove it! After shooting some available light shots with a wide-aperture lens, I quickly changed to my mid-range zoom, turned on the flash, and proceeded to get some neat f/4.5 1/8 second flash pictures of two wonderfully blurry people walking towards me. CF-3 set to "1" would have prevented that by locking the shutter at 1/200 and letting the flash expose.

[dpanicc1]

DAMphyne,

What you said makes sense to me. But it's what Chuck said that confused me because of ghosting. "...fill flash in low light..." with option 0 means the camera will pick a slow shutter speed and ghosting prevails.

It seems that it should read: fill flash in high ambient light for option 0; else, you get ghosting. Your (DAMphyne) explanation makes sense, but his mention of low light with option 0 just conficts with what I see.

[CoolToolGuy]

Is this a 10D thing, or does it pertain to all Canon DSLRs? It might help to slip the camera model in your post somewhere so everyone will know whether it pertains to them or not. 8) :) :D

Have Fun
Rick 8)

[DAMphyne]

This is experience I've had with both the D30 and 10D.
Low light is kind of a relative term, if you are shooting wide open with option '0', you should have a relativly short shutter speed, thus no ghosting problem. With a moving target, basket ball, volleyball, most indoor sports, the ghosting becomes apparent very quickly. (Don't rely on seeing this problem in the LCD screen)
If you can hand-hold at 1/60sec, and the subject is still, ghosting shouldn't be a problem.
If the shutter speed is too slow to hand hold, ghosting, and if the subject is moving, ghosting.
A shot at f2@1/100sec, you can hold, change to f5.6 the shutter speed is about 1/15 sec, too slow to hand hold.
Hope this helps

[dpanicc1]

Yes, sorry, 10D.

Thanks for the responses as now at least I can interprut what I am seeing and know why I am seeing it..., wouldn't want to shoot meaningful shots in Av unless I have a fast enough shutter speed, that's for sure.

[scottbergerphoto]

It seems that people are getting lost in Custom Functions and terminology without first thinking about what fill flash is and what you are trying to accomplish by using it. Fill flash implies that there is significant amount of ambient light and you want to "fill in" some shadows, such as on a sunny day and you want to put some highlights in the eyes. That means you are going to be setting your exposure for the ambient light in Manual, or Av, or Tv. The flash will add light to the foreground. You will usually want to reduce the amount of flash by 1 to 1 and 2/3 stops, so it just "fills in". You can do this yourself or try to get the camera to do it through it's Auto fill reduction Cfn.14. I prefer to do this myself. You can't always predict what the camera will do. In low light situations where you want to capture ambient light and add flash to light the foreground, such as a sunset or dim street lighting and you want to add some light to subjects in the foreground you need slow shutter speeds to capture the ambient light. After the flash fires, that light will reflect off the subject and give ghosting if the subject moves. This is called "slow sync" flash or "Night Portrait".
When people set Cfn. 3 to fix the shutter speed at 1/200 in Av, you are not going to get much of any ambient light recorded in low light situations. You are basically taking a flash picture, not flash fill and not slow sync. You are basically saying, "I don't want to worry about my shutter speed dropping in low light, fix my speed at 1/200."
IMHO some of th Cfn's make using the camera more complicated then necessary. If you think about what you want to do, you can just as easily do it in M, Av, or Tv, without having to memorize which Cfn works when.
The other Cfn's dealing with button assignment, AF assist,MLU are pretty useful. On the other hand, if they work for you, have at it!
Regards,
Scott

[Tom W]

It seems that people are getting lost in Custom Functions and terminology without first thinking about what fill flash is and what you are trying to accomplish by using it. Fill flash implies that there is significant amount of ambient light and you want to "fill in" some shadows, such as on a sunny day and you want to put some highlights in the eyes. That means you are going to be setting your exposure for the ambient light in Manual, or Av, or Tv. The flash will add light to the foreground. You will usually want to reduce the amount of flash by 1 to 1 and 2/3 stops, so it just "fills in". You can do this yourself or try to get the camera to do it through it's Auto fill reduction Cfn.14. I prefer to do this myself. You can't always predict what the camera will do. In low light situations where you want to capture ambient light and add flash to light the foreground, such as a sunset or dim street lighting and you want to add some light to subjects in the foreground you need slow shutter speeds to capture the ambient light. After the flash fires, that light will reflect off the subject and give ghosting if the subject moves. This is called "slow sync" flash or "Night Portrait".
When people set Cfn. 3 to fix the shutter speed at 1/200 in Av, you are not going to get much of any ambient light recorded in low light situations. You are basically taking a flash picture, not flash fill and not slow sync. You are basically saying, "I don't want to worry about my shutter speed dropping in low light, fix my speed at 1/200."
IMHO some of th Cfn's make using the camera more complicated then necessary. If you think about what you want to do, you can just as easily do it in M, Av, or Tv, without having to memorize which Cfn works when.
The other Cfn's dealing with button assignment, AF assist,MLU are pretty useful. On the other hand, if they work for you, have at it!
Regards,
Scott

Good post, Scott, and you're right - the CFn's can complicate things. But they can also simplify things. In my situation, setting CFn 3 to "1" would have been the right thing, since I was switching back and forth between regular flash and available light photography. I wasn't using fill flash at that point during the day.

I could easily have avoided blurring my subjects for a few frames had I switched to manual mode and made aperture/shutter adjustments myself or had I switched back to program mode. Of course, had I looked that that bright display in the bottom of the viewfinder in the first place, I'd probably have noticed that my shutter speed wasn't up to par for the task at hand. Then I could have avoided blowing 4 or 5 shots. :)

Anyway, chalk that one up to experience.

BTW, I did change CFn 14 - I was having some unpredictable results when it was set to auto-fill. I'm still experimenting with that one, but I think that I'm going to leave the "auto" off and set my own flash exposure decisions.