Need somethind wide...

So I am trying to narrow down my decision here for a nice UWA lens for some automotive stuff. I've got the 17-40L but on the 40D it's not wide enough and the Mk3 it feels a bit tight as well. The Canon 10-22 is nice, but unusable on my Mk3 which means I'd be subbing in the 40D for any UWA shots. Sigma makes the 12-24 which seems like a nice lens and will work nicely on the Mk3 and future FF cameras but then there's the Tokina 11-16 which looks to be a superb lens and I know picturecrazy here modded it to work with his 1D (crazy guy) but I assume stock it's only usable past 13mm on the 1D?

Price wise it's not much of a concern as there's roughly $200 difference between all three choices brand new up here in Canada.

Is it ok if I tell you that you can use the ef-s 10-22 on your MK III? I did. The rear plastic baffle is just pressed into place. Put your finger in side and pull it off. NOw the lens will mount on the MK III. As long as you do not see dark corners, it is OK to snap away (without hitting the mirror.) Works from about 17-22. Good quality as well. Ok, not a real solution but interesting.

Interesting trick, but with it only being usable from 17-22 I'm back in the same boat focal length wise at 17mm with the 17-40 right? I thought someone here had mentioned that the Tokina 11-16 will work at 13mm on the Mk3 unmodified?

Yes, the Tokina 11-16 will work from about 13mm on up. But, why not just get a lens intended for a FF/1.3 body? How about the Sigma 15/2.8 fisheye. Very nice effect when used on the MK III. Not too fishy but very wide, wider than the 10mm on a 1.6x crop if I remember correctly.

Get the 12-24, It'll knock your socks off! A mate of mine uses it for his 1D and 1Ds. Example from the 1Ds here: http://www.flickr.com …in/set-72157606579946451/

Archive of shots here: https://photography-on-the.net/forum/showthre​ad.php?t=298928

Yeah the 12-24 is quite tempting given that it works on FF, 1.3x and crop. I've been looking at picking up a FF camera since the gf said she'd put money towards a 5D or 5D2 as part of my christmas gift so having a usable lens across all 3 bodies would be nice.