Ken and Julian and all - Thanks, your explanations are making sense. Especially about the narrowness of the flash metering spot. I'd forgotten about that. At next weeks rehearsals I'll try being a little more precise.
However, let me ask for clarification an another point. This may seem really basic, but when you say "ambient" reading, you are saying something other then the EV reading of the shot without flash. For instance, sitting here in my average-lit room, if I take a reading _in P mode, using Partial metering - (I have 800 speed film in the camera right now) of the bookcase across the room with the flash turned off, I get 1/60 @ f/2.0. If I turn on the flash and let it cycle up, I get 1/60 @ f/4. This is without firing any pre-flash. Now as I understand it, when I actually fire the shot, E-TTL is going to do yet another calculation, and determine the flash duration. But 1/60 @ f/4 will still be valid, right? What I'm a little confused about is how the camera knows to choose f/4 when the flash goes on. Distance doesn't affect it, I tried focusing on something in the room, maybe 20 feet away, and I get the same reading. If I then go into Tv mode and select 1/60, I get f/2.5 with the flash turned on, and if I go into Av and select f/4 I get 1/20. I'm really not sure how the flash being on is affecting the metering. There are also, not surprisingly, reading different yet again if I switch metering modes while the flash is on. If I take a flash meter reading using the test button off the bookcase (8 feet away) I get 1/60 @ f/32 + 1/3 of a stop, leading me to believe that you are correct that the test button is just full power, and therefore useless for flash metering. Thanks for taking the time to address this. My brain feels a little muddled! Ken * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
