a proper 12-24 for full frame would be absolutely killer. the 16-35 just isnt sharp enough for such duty. I am iteching to go full frame but not having a 10-22 kinda sucks
The 16-35IIL really is sharp and far better than the ef-s 10-22. But it's a general use ultra wide, so it's not too angular distortion corrected. So it works well photographing landscapes and groups of people. Heavily corrected wide angle lenses are great for photographing building and things with straight lines but anything with a circle or curve gets distorted due to the angle of view....so people or groups of people get very out of shape. The 16-35IIL's achillies heel isn't it's sharpness (which most forums seem to spout on about) but it's CA and flare control. It's an old design and due for a new optical formular....but it's still younger than the vernable 17-40L.
The Nikkor 14-24mm is a great lens for shooting charts, but less so for real world shooting. The huge difficulty in fitting and using filters is big problem for landscape shooters (compare it to how easy 82mm filters are to handle) and due to it's recitiliear design, it's not that great for people shots. Yes it's very sharp wide open, but then again who needs really sharp corners at f2.8? Most landscapers stop down to achieve sufficient DOF and the 16-35IIL easily matches it by f8. For group shots, a bit of vignetting and corner softness looks nice.
Many of my pro photographer friends who shoot Nikon have all sold this lens and gone back to their older 17-35mm options. So I do wonder if a new Canon 14-24mm lens will be that useful if it behaves the same as the Nikkor version. For the extra 2mm wider angle of view and the PITA filter handling...Hmmm...