Canon flash problem on 5D MKII

[Stu Farnham]

I'm set upto do some close-up work as follows:

5D MKII
100mm f/2.8 macro (not that the lens matters)
ST-E2 tranmitter
580-EX and 430-EX speedlites, both set as slaves.

When I set mirror lockup and a 10 second shutter delay, both flashes fire at mirror lockup, and the 580EX fires again when the shutter opens.

I thought the 430-EX might not be ready to fire when the shutter opened, but a manual test shows that not to be the issue.

It strikes me as odd (at best) that the flashes fire at lockup.

Any thoughts? I am far from adept at flash photography (yet).

Stu

(I'm going to try this with live view and the mirror locked up, but even if that works the behavior I am seeing seems counterintuitive at best)

[Titus213]

Pre-flash? Not sure why the 430EX is not firing at shutter

[tim]

Does the ST-E2 have a test button? What happens if you hit it? If you have a 580EX master and hit test in master/slave the slave flashes about a second after the master. Try that with your 580/430, just to test communication's working. Also make sure the 430EX is seeing the flash from the ST-E2.

[Stu Farnham]

Both are set as slaves and both fire simultaneously under test.

[tim]

What groups and channels are the two flashes set to? What ratio type and ratio is selected? eg A:B or A:B:C 8:1

[René Damkot]

both flashes fire at mirror lockup, and the 580EX fires again when the shutter opens.
Actually, a bit before MLU ;) You should be able to see the flash through the viewfinder.
Pre-flash? Not sure why the 430EX is not firing at shutter

Agree.

[Titus213]

http://www.flickr.com/groups/strobist/discuss/72157603576931251/

Don't know the validity of those comments...