What flash slaves can be used with a Canon Speedlite 600EX-RT?

My current flash setup is a standard shoe mount but I've been thinking about getting a remote.

I've been drooling over the Speedlite 600EX-RT. It uses radio to control slaves, which is nice (longer distance, doesn't require line of sight, etc.).

One thing I don't understand: do slaves also have to be 600EX-RTs or do other flash units use radio to communicate already? Can any (cheap?) flash slaves can be used with a Canon Speedlite 600EX-RT or do I need to buy the 600EX and a ST-E3-RT transmitter in order (or multiple 600EX-RTs) to have a radio-controlled remote flash setup?

Answer

Unfortunately, no.

As of today (October 17th, 2012), built-in radio-controlled wireless flash setup with Canon 600EX-RT speedlites limits you just to two options:

• 600EX-RT master with 600EX-RT slaves


• ST-E3-RT master with 600EX-RT slaves

Optical wireless mode, on the other hand, allows 600EX-RT master to trigger non-600EX-RT slaves, but that's not what you are after.