> I have read that preflashes are not fired
> when the flash head isn't directly positionned
> right forward onto the subject. I'm used to use
> indirect light by turning the flash head onto
> walls/ceilings. Am I going to loose the 3D matrix
> metering system if I do so? If so, how will the
> F100 do to find the correct exposure?
The pre-flashes are used to detect highly reflective
surfaces in the image (like mirrors or white walls)
that aren't lit by the ambient light. If you bounce
the flash, you'll have to compensate for those yourself.
> Another question: When using slow synchro, is
> there a risk of fuzziness of the flashed image
> (the ambiance could be of course). Which is the
> duration of the flash?
Flash duration varies depending on the individual flash
and the amount of light required for correct exposure,
but it's always brief enough to freeze almost anything.
Even though the main subject will be sharp, it will
appear to have a halo around it if it receives a
significant part of its exposure from ambient light
at a slow shutter speed.
-Don
