I have another simple question. I'm practicing with my Canon 60D and an off camera 550 ex with the 60D internal wireless flash. If I buy the 430 ex ll or another 550 ex somewhere, will they all flash from off the camera 60D?
Thanks,
Art

Not my video, but this guy explains your answer perfectly.

Wireless Flash control with the Canon 60D - YouTube

Thanks for the forward. I have seen this before. I was thinking if I tried to use a mix match of flashes like one on a backdrop and another as a hair light would they all work together by the internal control but I guess if as long as they are in the line of sight, they should work.

Thanks for getting back with me.
Art