D7000 + SB-700 Commander mode question

Started May 27, 2012 | Discussions thread
Forum ProPosts: 10,360
In reply to Graystar, May 27, 2012

Graystar wrote:

When you use the built-in flash or an external CLS flash pointing forwards, the flash power will be determined by the focus distance. This is the most accurate way to determine flash power. Although ambient light is also accounted for in the power calculation, the distance is such a large part of the equation that you can actually change the flash power by changing the focus point. If you bring the focus point nearer to you, flash power will drop. Focus beyond your subject, and you'll get overexposure.

When you take the flash off the camera, the camera can no longer use distance to determine the flash power because it has no idea how far the flash is from the subject. So it has to rely on the i-TTL exposure. In this specific instance, I'm going to guess that you have white walls and ceilings? That would cause the shot to underexpose. It's exposure 101 all over again...too much white fools the meter...especially if you also have mirrors.

Now...if your ceilings and walls aren't white and you don't have mirrors...then I dunno...works for me!

First off, I'd like to thank all who responded, you've all been helpful.

It would appear this seems to be the issue .... and that the focus distance information isn't being transmitted to the remote flash by design. Which I guess makes sense because if you had the remote flash set up between the camera and the subject the resulting shot would be massive over exposure. Still, with the communication capability of the camera to the flash unit ... there should be in my opinion a means for the camera to send the focus to subject distance to the flash in such a manner that the camera can determine how far away the flash is from the camera... this way, all informational parmaters for proper TRUE iTTL off camera exosure would be met.

Thanks Graystar for solving this annoying year long puzzle. I had been working around it by .... as you put it.... old school exposure calculations.... as it would appear I'll have to continue doing.

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Nikon AF - One Shot ..... One Kill

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