Using on-camera flash to trigger speedlite slaves?

[Triptoph]

Is it possible to use a 30D's on-board flash to trigger my 580 EX II as a slave? I put the 580 EX II on slave mode and fired at it but it did not appear to fire; seems like this should work?

[Curtis N]

The built-in flash on Canon cameras has no E-TTL master capabilities. Additionally, the E-TTL pre-flash tends to trigger traditional optical slaves prematurely.

In order to use Canon's wireless flash system, you need at least one flash unit with master capabilities (or an ST-E2 transmitter) and at least one flash unit with slave capabilities.

[Triptoph]

Thanks Curtis.

I had read that the flashes could be controlled by a series of flashes, so i thought this may work. What if we forget ETTL? Using the 580 EX II on a manual on Slave mode, can I get the 30D to trigger it?

[DealsGapCobra]

It really is too bad that you can't disable the preflash on the built in unit and set the power manually. Well, at lest for us cheapos!