Wide angle flash..

I'm looking at getting the Sigma 500 DG. I'll soon have the Tokina 12-24. I know the Sigma comes with a panel to use it up to 17mm. How would I go about using the flash on anything wider? Diffuser? My search really didn't help me on this one..

with a FL at 12mm, its very hard to get an evenly lit picture with a flash. you are going to experience light falloff on the outer edges.

i dont think a diffuser will help too much, but the wide panel thing that you pull out on most flashes helps it a bit.

Is that up to 17mm on a FF camera? If so the 12-24 only goes down to a 19mm FF eq so you will be fine with the on board panel.

If you have a decent surface to bounce off of, that will probably do the most good. Once in a while I will drop the diffuser panel on my flash and bounce off the ceiling. It takes some power, but helps give fairly even light.

12mm on 1.6x is 19.2mm angle of view. You're good to go there. You should be bouncing flash anyway.

Yeah, I guess i forgot out the crop factor involved!