17mm Comparison: f5.6

Stopped down to f5.6, the Nikon improves considerably centre frame, to the point where the pair are hard to separate: honours here just about go to the Nikon on close inspection.

Canon 16-35mm f5.6 (centre)	Nikon 17-35mm f5.6 (centre)

 

However, the corners are even further apart: here's a 100% crop from the extreme top right this time.

Canon 16-35mm f5.6 (corner)	Nikon 17-35mm f5.6 (corner)

100% crops from the extreme top left show a similar performance gulf.

Canon 16-35mm f5.6 (corner)	Nikon 17-35mm f5.6 (corner)