Quote Originally Posted by peety3


The trigger doesn't know and doesn't care. You can easily have a bank of 12 flashes (or up to three, as Canon wireless supports three groups A/B/C). During the E-TTL process, the group fires a test flash at a low power (maybe 1/32, I don't know if this is public knowledge at all) and the camera meters the result. Every flash in the group fires at 1/32 for the test flash. The camera figures out what power level is needed, and commands the group to fire at that power. If the power level is 1/8th, then every flash in that group will fire at 1/8th for the picture. If you had a 580 and a 430 in that group, they'd each fire at 1/8th, so there would be less light coming from the 430 than the 580, but the camera would be happy.
<p style="CLEAR: both"]
<p style="CLEAR: both"]Doy! I forgot about the test flash [:$]
<p style="CLEAR: both"]Cool pic by the way. I love the tone. It feels like wintery light.