I have a Sunpack PZ-1 dedicated TTL flash and I use it with an EOS 1000fn (rebel sII). I would like to know which of the flash features are available with my body and which ones are not. How does my flash knows the amount of light needed, I mean, does it determine it during the exposure or before, (or when?). Thanks.

-- Javier Boscolo (jboscolo@ciudad.com.ar), November 15, 2000

Answers

I don't know what features the PZ-1 offers, but the Rebel IIS didn't have too many options anyway. It can use basic TTL and A-TTL I believe, but the Sunpak only does basic TTL metering. That's OK since A-TTL wasn't worth much.

What TTL (as referenced to flash metering) means is the flash exposure is measured "Through The Lens" as the exposure is made. There is a little light/flash sensor in the camera (at the bottom of the mirror box) that looks back at the film as it's being exposed. When this flash sensor determines that enough light has reached the film it tells the flash to stop. Exposure is determined by the durration of the flash. Usually from 1/1000 to 1/100,000 second.

-- Jim Strutz (j.strutz@gci.net), November 16, 2000.