Wireless ETTL problem - Rebel 300D + NEW Sigma 500 DG super EO

[eljustino]

I have two brand new Sigma 500 DG Super EO flashes. I wanted to try wireless ETTL - in particular I wanted to have the main flash on the camera off, and expose the picture using the slave only, but with the benefit of full metering and no cables!

The flash works OK - nicely - with my Canon 300d as a single standalone unit, but wireless ETTL does not work properly. I suspect a compatibility problem - this seems to be a very new version of the Sigma 500 DG Super - the "EO" designates E-TTL II compatibility ie for the newest cameras. Sigma's web page claims full compatibility, but...

If I follow the "correct" procedure for wireless slave with master flash on, it seems to partially work (ie both flashes fire) but the picture is generally quite overexposed. (The master and slave flashes are channel 1, the slave is ID#1 and the ratio is 1:1)
If I follow the "correct" procedure for main flash off, I get no flash exposure at all in the photo taken, although you see both flashes firing briefly - presumably just control pulses before the shutter opens but no actual flash to expose the picture?


I tried a work-around for "master off" whereby I set the main flash in ">1 flashes with ratio enabled". This then fires the slave only (as required) but generally UNDERexposes.

I seem to have the choice of over- or under-exposure and the "correct" procedure in the manual does not work. I'm sure that this new E-ETTL II flash has a problem with the 300d.

Any comment?

Thanks!

[PacAce]

I had the exact same inconsistant behavior from my Sigma EF 500 DG Super where it would over-expose, under-expose, and on rare occasions, expose correctly. But I was using the EF 500 with my Canon 550EX and 420EX flashes so I thought it was an incompatibliltiy problem between the Sigma and the Canon flashes.

I wrote to Sigma Japan about this problem and their response was that their flashes work perfectly fine with other Sigma flashes in wireless mode and that they do not guarantee compatiblity with Canon flashes.

Needless to say, I ended up returning the Sigma flash and will be getting a Canon 580EX instead.

Anyway, I find it interesting that you're having the same problems I was except you're using nothing but Sigma flashes. I wonder what Sigma Japan will have to say about that? BTW, if you're interested in the email address of the person I was communicating with regarding this problem, here's his email address:

Denju Matsumoto
Sigma Corporation
dmatsumoto@sigma-photo.co.jp

Good luck!

And one other thing, the EO designation of the Sigma flash is just a marketing gimmick. There really isn't any difference in the internals of the old and new EF 500 flashes as far as ETTL-II compatibility is concerned since ETTL-II (and ETTL) logic is built into the camera bodies and not into the flash units. That is, unless they fixed something that wasn't reversed engineered correctly in the first place. See:

http://www.sigmaphoto.com/faq/faq.asp?navigator=5

[eljustino]

Update - I have a formula which seems to work now. What I want is "master off, slave as main flash" - ie wireless off-camera flash.
1: Set slave as group 2
2: Set master for "slaves 1&2 with 1:1 ratio" ie "12 1:1" setting NOT plain "1:1"
3: Add +2 stops FEC on master

Clearly this is ridiculous but it does seem to work!
I find that "master+slave on" works OK generally but seems to overload in a small room.