Team me stuff, O flash masters

I have (4) AS-201 strobes and I am having what I hope is a simple problem.

Here is my setup for my test:

Canon 7D
Canon 430EX
(1) AS-201 connected by PC Sync
(1) AS-201 triggered by optical sensor on unit

I cannot get the Britek's to sync fire with my camera if I have my 430EX firing from my cameras hotshoe. Once I take off the speedlight and trigger them with the PC Sync cord to one of them, they both sync up fine with my camera.

Also will not work with the on-board flash.

I also tried this on my 40D and have the same issue so I'm betting it's not the camera?

Tried shutter speeds from 1/60 to 1/250 with the 430EX firing 1st and 2nd curtain sync.

Any suggestions or tips would be GREATLY appreciated.

The problem is that you are using the Canon flash units in ETTL mode, and they are emitting a pre-flash (for the purpose of calculating necessary flash output for proper exposure) which is triggering your strobes' optical slaves too early.

If you put both the camera AND 430EX into manual exposure modes, then you can use the 430EX to trigger the optical slaves on the strobes. You can never use the pop-up flash to trigger the optical slaves (without doing some goofy work-around procedures that I cannot describe), as there is no manual setting for the pop-up flash.

Skip nailed it.

SkipD wrote in post #9698899
The problem is that you are using the Canon flash units in ETTL mode, and they are emitting a pre-flash (for the purpose of calculating necessary flash output for proper exposure) which is triggering your strobes' optical slaves too early.

If you put both the camera AND 430EX into manual exposure modes, then you can use the 430EX to trigger the optical slaves on the strobes. You can never use the pop-up flash to trigger the optical slaves (without doing some goofy work-around procedures that I cannot describe), as there is no manual setting for the pop-up flash.

True for just about all EOS DSLR cameras except the 7D which does have manual capability with the built-in flash.

PacAce wrote in post #9699535
True for just about all EOS DSLR cameras except the 7D which does have manual capability with the built-in flash.

Yep. I played with that feature too. Didn't play enough to make it work though

Thanks guys.

Appreciate the writeup Skip. I'll try it out soon and report back.

Well, not much to report other than that you are correct.

Working great. Thanks again.