Does Canon have a detachable flash head comparable to Nikon's Speedlight SB-80DX that is triggered by another flash (no wired or wireless triggering necessary)?
Dang, I cant believe they dont include that tech in all the Canon flashes. I had to do some searching after coning across this thread. Apparantly Canon has some proprietary trigger tech they try to make people use.
Fwiw YN 560s have a slave mode and whatever the comparable Yongnuo unit to a sb 80 is it will probably offer S mode also.
Mike is correct. All of the flashes that Canon currently produce do NOT have a built in optical slave trigger. Which, to me, seems silly to not include. It's the main reason I switched from my 600EX's to the Phottix Mittros+ flashes. As Mike also points out, you can buy an accessory optical slave trigger but my experiences with these has been hit and miss. They're not always reliable. If built-in optical triggering is what you need, look to Phottix, Yongnuo, et al.