I have two Sigma flashes - both EF 500 DG Supers, one that's labeled for ETTL-II (though, as I understand it, there's no difference).
I mount one on camera, set it as the master on C1 wireless, and push + until the flash sign with a cross through it appears, which should mean that the master won't fire.
When I take the picture, the master and slave both fire, but neither offers illumination for the exposure... it's like the slave isn't firing in sync with the shutter. This is at all shutter speeds, so the flash sync isn't an issue
Thoughts? This happens both on a 1D MKII and a 20D.
And sometimes, after I fire the shot, the slave fires its modeling light (without me having touched the lens stop-down button)
I've run into this too. I have two Supers and have struggled the same. I think the flash you are seeing is pre-flash for exposure but the main off-camera flash does not fire. I fiddled forever trying to get wireless E-TTL to work with my XT and have had no luck.
Don't want to hijack this thread, but I do have one 500 Super (EO-ETTL) and was thinking about getting a second one.
Why would I want a second Super, but not just ST ?
btw - before getting my 500 Super I emailed Sigma and was told to make sure I get the EO-ETTL, otherwise it won't use ETTL II capabilities of the 20D. Don't know if mixing them will be an issue
