hi guys, might I asked what would be the best widest UWA lens for the said camera?

I've let go of my 17-40L already eh

16-35 F2.8. You may want to go with 12-24 from Sigma if you are in a budget.

sigma 10-20, i think you can use that and the reviews say it is blow for blow as good as the 10-22 EFS which your body cant take

The Sigma 10-22 may 'fit', but it was also designed for APS-C sensors so even though the mark IIN is NOT a full frame, it's still larger than conventional APS-C. I don't think it will work as well. The Sigma 15-30 was designed for Film SLRs so you might have better luck.

But if you already have a IIN, why settle for anything less than a 16-35 F2.8 L?

you can't go wrong with the Canon 16-35 F2.8L, proud owner of one.

ahh thanks dave. how about the 12-24 tokina then. the 2.8L may be a bit steep hehehe price wise

you'll be better off with the sigma 12-24. it's for full frame (though yours is a 1.3x crop).

ultra wide angles: canon 10-22mm, sigma 10-20mm, tokina 12-24mm, and tamron 11-18mm - all are designed for the dslr with a crop factor of 1.5x or greater.

[caveat]
however, there has been a test, fitting the sigma 10-20 to a dslr with a crop factor of 1.3x and it did not cause vignetting from 11-20mm. you might want to give it a try. :)

i agree with aris, go with the sigma 12-24 if you really want UWA... but i personally prefer the 16-35L if cost is no object :)

i own a sigma 12-24 and 1DMk2N. The combination ain't that great. It's soft in the sides. Must be a bad lens I got. Else, 17-40 at least... or better yet 16-35.

My combination:
1Dmk2 - 16-35 f/2.8
1Dsmk2 - 14mm f/2.8

http://www.pbase.com/manilaman04/image/40602994/medium.jpg
http://www.pbase.com/manilaman04/image/40839276/medium.jpg
1dmk2 with 16-35 f/2.8

Used to have the 10-22mm when i had the 20D; match made in heaven

Also, had this dliemma. These good lenses won't work for the 1D or full-frame cameras: Tamron 11-18, Canon EFS-10-22, Sigma 10-20, Tokina 12-24. The UWA's are mostly designed for APS-C, since the 1DmkII is 1.3 crop corners become dark. Of all the lenses I have tried, the Sigma 12-24 is the only usable zoom which is designed to work for film cameras as well. But yes there are quality issues with this lens so test the copy before you buy. I ended up getting a Sigma 14mm f2.8 prime second hand to fit my budget too.