Turn off master flash - Canon 580EX

I've read thru the manual and all of the stickies and cannot find out how to disable the master flash using the canon wireless ettl system. I tried turning it from on to off and the ratio to off and I still get flash in my shot. And no, I'm not talking about pre-flash

Using a 5dm2, 580EX & 430EXII

Even when the master is turned off, it still fires a command flash to give instructions to the slave. It's a weak flash that generally does not significantly contribute to the exposure.

I noticed the same thing a while ago and I think Curtis may have even helped me then too.

If I remember correctly the manual does a poor job of explaining this. Yeah, you will see a flash and in some cases it does affect the exposure but not much. It took me a while to figure it out as I thought the wireless communication was exclusively with IR light and I was wrong.

I tried and tried to search last night for answers but have found some from PacAce about this same subject which explained a lot.

It was completely lighting my image which is what is frustrating.

I'm going to play again with it tonight and change my settings - I was at 2.8 @ 1600iso which may be why it was showing up.

So would it help to swivel the master and point it right at the slave rather than the subject?

hairy_moth wrote in post #7833890
So would it help to swivel the master and point it right at the slave rather than the subject?

As long as the slave catches a glimpse of the flash it will work so you should be able to point or limit that flash as long as it triggers the slave.

Some have even suggested putting on an IR filter. Is it still a filter if it lets IR light pass? Anyway, block the visible light and only let the IR through to the slave.