I borrowed this off a friend and his 5dMkIII to test. I will be doing a video review on this when I have time to edit the footage.
As far as I can see it's only Canon and Nikon mounts. Beast of a lens some heft but very well built and I'm impressed with the image quality, it's very usable wide open across the range. Even at 24mm the corners are not horrible (of course not tack some softness not much though)
It does pick up when stopped down even slightly (contrast). I'll be honest though much as this is a killer combo (AF is very fast) it's heavy I'm so used to crop sensors this would really weigh me down shooting for an afternoon. I am moving more towards photo reviews I have another flash in to test so stick around folks