First, I apologize if this is a redundant thread, but my search has not worked with this forum for a couple of days, so I'm just gonna ask... I am wondering if someone could give me a better understanding of external flashes (master vs. slave, TTL dedication, metering...) I am working with Canon, so anything specific to this, would be great. I am interested in being able to use an external flash to bounce while attached to the camera body and would also like to be able to use the flash externally/wireless while detached from the camera body. Additionally, I would like to be able to add another flash in the future to use simultaneously (I guess this would be a 'slave' flash?). I am looking at the "580 EX II Speedlite"... would this accomplish what I am looking for?