Tokina or Sigma? What do you guys think? I want a lens that ends in 24 as I am going to be getting a 24-70 2.8 lens. The sigma is probably easier to find used. I've heard something about soft copies of the Sigma, but I don't know, I haven't done much research. I'm scared of the build quality on the 10-22 Canon and the fact it's EF-S. I'm more inclined towards the Sigma cause I have a feeling I can send it to get calibrated easily, and because I am probably going to be getting the Sigma 24-70.

I doubt you would have much use for the 10mm end on a FF body, so just plan on selling it when you/if you go to a FF body (you'll want the 16-35 then anyway)!
