> I have the following problem which I cannot solve based on the >manual. I use EOS 3 and two flashes: 550EX and 380EX . One flash is >connected directly to the camera. Second flash is connected using a >standard >(non-Canon) cable to the socket for external (non-Canon) flashes (e.g. >studio flashes). > > What I do not know is if EOS 3 during light evaluation takes this >second flash under consideration. In other words if I have Av mode turned >on >the main flash will fill-in and the second flash? Will it also fill-in so >the picture is taken properly or will it just "fire" and the picture is >overexposed? Does E-TTL or TTL work with second flash? ... > Michal Birnbach
Also I think the second flash will fire at full power. So even if you would use TTL (instead of E-TTL) in the main flash you will mosty get overexposed photos. Why? I assume the flash duration (at maximum power) is the same for both flashes. So when you trigger the shutter both flashes get ON at the same time. When the camera thinks there is enough light it shuts the on-camera flash off but the off-camera flash still continues ON until all power is output. You might get lucky if your subject was close to the maximum reach of your total flash output power. If you used E-TTL instead of TTL you would get probably even more overexposure because - as others said - the secondary flash would not participate during the preflash. If the flash beams are not overlapping then you might succeed by manually calculating the aperture for the second flash (based on GN) and letting the on-camera flash use (E-)TTL with the calculated and selected aperture. This might work in some cases but if you have a flash meter having both flashes on manual would be the best solution. Vesa _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
