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Understanding flash

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rskoss

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I don't know how much of this is a D700 thing or how much is a lighting thing but I'm posting here so at least we're all on the same page w.r.t. the operation of the camera.

I'm trying to photograph my iPhone to sell on eBay, but I'm interested in learning product photography to I'm trying to do this "right" to learn as much as I can. I don't have a lot of experience with flash so maybe everything is working as it should and I just don't know it because I have nothing to compare what I'm seeing.

The setup is D700 using the pop-up as commander (but set to TTL mode). I have an SB800 pointing down on the iPhone through tissue paper to diffuse it and another SB800 to the left of the iPhone, also through tissue paper. The tissue paper is white (like what clothes come in when you get them as a gift). 24-70 at 50mm, 2.5 feet from iPhone. Aperture priority mode.

I wanted to get max depth of field, so I have the lens stopped down to f/16. Even with all three flashes dialed in with +3.0eV compensation, the shutter stays open for 25 seconds. That's my problem/question. With all that light, why is the shutter staying open so long? I guess there's no problem doing a time exposure like this since nothing is moving (camera is on a tripod) - but it just seems very weird with 3 flashes.
 
Try shooting in manual mode - the flash duration is fast I don't know quite what's wrong in yr set-up. Usually the d700 goes straight to 1/60 in Aperture Priority when u pop the flash up. Have you gone into the commander menu and set yr SB800s from there? Try manual and TTL - good luck - someone who knows better will doubtless chime in. (You're going to start losing detail to diffraction @ f/16, despite DOF.) Also, try shooting at a wider aperture - aperture controls flash, or something like that :)
 
Shoot in manual....

Flash set on TTL-BL?
 
When you're using TTL, the camera should be set to manual, as others have mentioned.

You are seeing the camera metering as though you were not using flash, thus, you're really supplying fill flash. The exposure the camera is giving you as you have it set would be the proper exposure for natural light.

I don't know how well the tissue paper will work, but I might just bounce the flash off some foam core boards if you don't care for the results you get from the tissue.
Sarah
 
sjessup said:
When you're using TTL, the camera should be set to manual, as others have mentioned.

You are seeing the camera metering as though you were not using flash, thus, you're really supplying fill flash. The exposure the camera is giving you as you have it set would be the proper exposure for natural light.
Click to expand...
Now that's interesting and I believe it's the hole in my misunderstanding of using flash. What little flash stuff I've done up until now has been exactly that - balancing flash with ambient, i.e., using it as fill. What I'm doing here is completely different - there is no ambient, all of the light is coming from the flashes.

This also explains why people use light meters in a studio - something else I could never figure out since the camera has a light meter.

So much to learn.
 
Hi,

perhaps I'm missing something, but I don't think Sarah's explanation is quite sufficient to answer your question. I've just repeated your setup, and my camera will switch to its slowest flash shutter speed which in my case is 1/60 second. The only way to get slower than that in aperture priority mode is either to shoot in slow / rear sync (which you said you are not), or to dial in a slower flash shutter speed in custom setting e2. Is there any chance that you changed your flash shutter speed setting (e2) at some point?

Steve
 
doctorstevo said:
Hi,

perhaps I'm missing something, but I don't think Sarah's explanation is quite sufficient to answer your question. I've just repeated your setup, and my camera will switch to its slowest flash shutter speed which in my case is 1/60 second. The only way to get slower than that in aperture priority mode is either to shoot in slow / rear sync (which you said you are not), or to dial in a slower flash shutter speed in custom setting e2. Is there any chance that you changed your flash shutter speed setting (e2) at some point?

Steve
Click to expand...
e2 is set at 30". Not sure why, I don't remember ever setting it.

Setting it to 1/60 like you have yours makes the setup behave "normally". Of course everything is now underexposed - but I can fix that.

Looking for a reference on how all of these parameters interact....
 
Tissue paper is fairly opaque, may not
be transmitting much light.

Try no tissue and bouncing the light off ceiling and walls.

For some reason, very little light is reaching your subject.

maljo
 
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