Joe Wilensky <[EMAIL PROTECTED]> wrote: >Here's a question about dialing in flash compensation, especially in >a situation like daylight fill flash and with a camera like the PZ-1p. > >The TTL flash sensor measures basically like a centerweighted or >averaging meter, just measuring the reflection off the film itself, >correct? Assuming an exposure in daylight where you let the camera >meter handle the ambient light, let's say you dial in -1 stop TTL >flash compensation, or -1.3, or -1.5, etc. How does the TTL sensor >differentiate between the light reflecting off the film from the >daylight-lit exposure and the flash burst?
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 Roberts Photography and writing www.robertstech.com
