Hi All,

I have a 20D and 5D (and soon a 40D!!) and 550EX flash unit. I want to add a second flash (430EX or 580EX) and just want to confirm that full wireless control will be achievable between the two generations of flash. I bought the 500EX new in 1999 and it is still going strong trillions of flashes later (OK, maybe a slight exaggeration).

Thanks for your help ,

Andrew

Yes, it will work wirelessly with canons IR system.

Ya, with ST-E2, you can also control the output from A devices and B devices, but you have to channe the flash right to make it work that way. All the later flashes from Canon work with this.