"Boris Liberman" <[EMAIL PROTECTED]> wrote: >>It doesn't. TTL flash controls flash exposure by varying the >>*duration* of the flash, not the power. So... During TTL flash exposure with >>-1.5 stop compensation, the system will shut off the flash (this happens >>in milliseconds) when the amount of exposure has reached 1.5 stops less >>than the meter deems necessary. The *shutter*, however, will remain >>open for the necessary amount of time for proper, uncompensated, exposure. >> >>So what you have is a combination of ambient exposure at standard and >>flash exposure at -1.5 stops. > >Mark, this is probably the bit of knowledge that I did not have.
Heck, *I* didn't have it until relatively recently! I was using flash compensation fairly successfully without really understanding how it worked. >My >(wrong) understand was that by issuing exposure compensation at, say >-1.5 stops, I actually let 2^1.5 less light strike the film. That's true if you set EXPOSURE compensation at -1.5 stops. But that's not the same as setting FLASH compensation at -1.5 stops. >So in a sense I thought that even when using the flash one still >thinks in terms of integrated exposure, so to say. To do that you'd need to set *both* exposure compensation *and* flash compensation. >Well, I think I am proven wrong by your explanation and by my lack of >successful photos while using the flash - both built-in in ZX-L and >with AF220T that I had on loan... > >Wisdom of PDML is indeed infinite <grin>. I'm still learning from it every day ;-) -- Mark Roberts Photography and writing www.robertstech.com
