Tokina AT-X 16-28mm F/2.8 Pro FX Canon
Canon EF, full size
Tokina AT-X 16-28mm F/2.8 Pro FX Canon
Canon EF, full size
In terms of sharpness, this lens is first class. The only disadvantages I have noticed are the relatively heavy weight for travelling and the lack of a thread for attaching filters (as the lens is curved).