Turning masterflash off while using slaves (550s)

[Norman]

I have multiple Canon 550EXs. I cannot get the master flash not to flash while using the slaves. I looks right on the panel - according to the manual. But no luck.

Also, is my Canon 10D and 20D Type A or B bodies?

[nkg]

You press SEL/SET to turn the master flash on or off. In the off position it still controls other flash units but doesn't emit any scene-illuminating light. However, since it uses visible white light to control the slave units you'll still see a pulse of white light.

All EOS digital cameras since the D30 are type A bodies since they use E-TTL for flash. In fact, they can't use TTL or A-TTL for flash.

[Norman]

Thanks a lot. It seems to flash at the same time. I would have expected a delay in the slave and a less strong light from the master.