I've noticed a few quirky things with the Sigma EF-530 DG Super flash unit that I recently acquired and wanted to check with other owners to see if these are typical.
1. In eTTL slave mode one can set the "Slave Unit ID" to 1, 2, or 3 which are equivalent to the Canon slave ID of A, B, or C respectively. This is in the Sigma manual on p. 21. What I have noticed is that if you select ID = 2 or 3 you are OK as long as you never change the mode away from eTTL slave mode. As soon as you change the mode the ID goes to 1 even if you cycle back to eTTL slave mode. So moral: set it and don't cycle through other modes or you will have your Slave ID reset back to 1.
2. I have a 580EXII that I use as a master, but also checked out if the Sigma could be a master (as advertised) on-camera and the Canon as a slave (don't ask why I would want to do this, I was just curious). Anyways, the Sigma is not recognized as a "master" by my 40D body the way the Canon 580EXII is.
With the Canon as a master, a new menu option "Wireless" appears under the "Flash control" option where I can set flash ratios for eTTL and manual flash power(s) for flashes in groups A, B, C directly with the menu controls in the 40D body.
With the Sigma as a master, the "Wireless" menu option under "Flash control" does not appear. I have to use the buttons and LCD on the Sigma itself to set these parameters.
3. Furthermore, on the Sigma the "flash ratio" of ID 1 to ID 2 only goes from 8:1 to 1:1 while the manual states on p. 22 that it goes from 8:1 to 1:1 to 1:8.
4. I cannot get LCD to appear like the first figure on p. 21 of the manual. I get a single (1) lightning icon directly under the first T of eTTL instead of the big/small double lightning icon. When I switch to slave mode, I get the double lightning icon and the SL letters to indicate wireless slave mode. I attribute this discrepancy between the manual and the flash unit to the lack of an update to the manual.
So for other Sigma owners, does the above match your experiences as well? I'm just curious if I have missed something which is easy to do when all you've got is the Sigma manual. (I did figure out the "press and hold Sel for 2 seconds" to switch to Manual master mode (p. 23).
Thanks for any comments and responses!