550EX/40D flash exposure question

Look at these two snapshots and see if you can offer some guidance as to why the 550EX/40D combo would use a nice amount of flash indoors, and then a large amount of flash outdoors.

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Outdoors, the background is dark and far away and only grandma is reflecting light back to the lens. Indoors, you have white walls reflecting light back to the lens.

What mode of exposure metering are you using? I like "Partial metering". I think the default is "Evaluative metering", see p. 92 of your 40D manual.

It's all about the background.

The indoor shot has a close, white background to reflect the pre-flash, while the outdoor shot has a distant background with only the subject reflecting significant light from the pre-flash.

Even though Canon claims E-TTL II can find your subject and expose accordingly, I find that the presence of a close, bright background can affect the flash exposure dramatically.

I was in evaluative metering, no EC/FC. This is a shot moments later w/o flash at the same aperture. The shutter speed was only a a hair slower (1/13 to 1/15). (Trimming these since I know the other people would not want their pictures posted.)

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In this situation, I would just look at the pic in the LCD, then make a quick FEC adjustment and retake. Repeat until satisfied. I think I could do 3 shots in 10 seconds. I've left my 40D in "partial metering" mode since I first bought it. I shoot mostly sports and people where I'm mostly interested in what's going on near the center of the field of view.

Something you can try:

After locking focus, recompose so that the persons face is dead center (still with the shutter half-pressed) and press the * button for FEL. Then immediately recompose and complete the shot.

And wow ... everyone sure stood still for you to get such a good capture at 1/15s

For this case I probably would have used flash with the camera in Manual at 1/60s to 1/100s and f/5. But my kids don't stay still ... so what do I know

Curtis, going to read your links!

40Dude I hear you and Curtis both on the background. Time wise, I'm sure I can't match your chimp and adjust speed. I can't see the LCD well or read the menu with the glasses on, can't see worth a darn more than 10 feet away without them, absolutely can't stand bifocals or the blended lenses. (Getting older fast!) I'll try the more restricted metering modes in the near future.

Bob, I'll try the face centering, FEL advice as well. I had a few shots that were blurry. I was thinking (after the fact of course :rolleyes that I should have set the ISO up to 200 and/or opened up another stop on the aperture. I just have started using M in ambient conditions, haven't even really tried using flash in M mode yet since I'm obviously still in the early learning curve with flash in Av/Tv, but I will.

I really appreciate the feedback!

I have DefinityII progressive lenses for my eyeglasses. Have you seen them? They are quite different than other progressive lenses. Check with your eye doctor next time you go in.

StarJack wrote in post #6955676
Curtis, going to read your links!

Curtis is the Master of Flash (for some reason I think of something else when I hear the term "Master Flasher") ... he always gives solid advice

StarJack wrote in post #6955676
I can't see the LCD well or read the menu with the glasses on, can't see worth a darn more than 10 feet away without them,

Hopefully you have your camera's diopter adjusted for your vision. You should be able to adjust the FEC without removing your eye from the viewfinder.

Curtis N wrote in post #6955930
Hopefully you have your camera's diopter adjusted for your vision. You should be able to adjust the FEC without removing your eye from the viewfinder.

Yes I do, no problem really seeing through the viewfinder. And I was picturing using the FEC ON the 550EX, not using the EC on the Quick Control Dial on the 40D. From page 36 of the 550EX manual, "You can also use flash exposure compensation in combination with normal exposure compensation (to control the background's exposure level) in a flash picture." So I was thinking FEC on the 550 is dialing up/down the flash power, and the QCD is altering exposure for the scene, based on what metering mode I'm in.

So am I misreading the 550 manual, or misunderstanding what 40Dude was meaning, or both!?

I'd adjust FEC on the camera body. Click on the ISO/FEC button with your right index finger (top right of camera), then spin the thumbwheel with your thumb. No need to take your eye off the viewfinder. However, to look at the pic on the LCD you do need to take your eye off the viewfinder. I have pic review set to 4 seconds, so the pic is on the LCD for that amount of time.

PS: After pressing the ISO/FEC button, if you don't want to change the ISO, don't spin the fingerwheel.

OK, thanks! And in relation to being faster/easier I certainly understand. But in relation to my OP, why I wouldn't just adjust the FEC on the flash unit itself, if I'm happy with the scene exposure overall? Let's say I'm in Av, if I use the QCD to alter EC then I'm changing my shutter speed. But if I use FEC on the 550 then I'm just altering the amount of flash being used w/o out changing the shutter speed?

You can adjust FEC on the flash unit or with the camera. Your choice. I recommended the camera method for you because you can use the viewfinder with its diopter adjustment for your eyes.

Either way, it's different than EC. It's adjusting the flash power. Re-read your camera's instruction manual on Flash Exposure Compensation.