Thanks wombat! Any comments on how its resolution compares to a 17-55 f/2.8 (which is what I have now). I would love to not be able to take a hit in sharpness.
The 16-35L II is very slightly
less sharp than the EF-S 17-55mm when both are used on the same APS-C body. The difference can be detected in controlled tests (I've done some with my 7D), but is not really evident in real-world shots.
If you need to go wider than 16mm, your only weather sealed option is the EF 14mm f/2.8L II (or the 8-15mm f/4L Fisheye, but I presume you want a rectilinear lens).