Resolution (f5.6)

Nikon 17-35mm 2.8 v Zeiss 21mm 2.8 v Canon 17-40mm f4 L

21mm at f5.6 (Zone A)
nikon 17-35mm f5.6 Canon 17-40mm f5.6 Zeiss 21mm f5.6
Nikon 17-35mm at 21mm / f5.6 (centre) Canon 17-40mm at 21mm / f5.6 (centre) Zeiss Contax 21mm at f5.6 (centre)
4.6 points
4.7 points
5 points

Full marks is the only possible response to the Zeiss 21mm at f5.6: fully resolving to the limits of the sensor. You could put a Leica APO Macro, Canon 200mm f1.8 and a Zeiss 85mm f1.2 alongside this capture and it wouldn’t look any better on a 5D. One stop down, the Canon 17-40mm once again impresses, marginally outperforming the Nikon here again.

Performance at f5.6 (Zone B: Left Side)

nikon 17-35mm f5.6 Canon 17-40L f5.6 Zeiss 21mm f5.6
Nikon 17-35mm at 21mm / f5.6 (mid-frame) Canon 17-40mm at 21mm / f5.6 (mid-frame) Zeiss Contax 21mm at f5.6 (mid-frame)
4.4 points
4.5 points
4.8 points

Barely compromised in Zone B at f5.6, the Zeiss 21mm comfortably outperforms any comparable lens at this focal length. The Canon and Nikon are practically level-pegging.

Performance at f5.6 (Zone C)

nikon 17-35mm f5.6 Canon 17-40mm f5.6 Contax 21mm f5.6
Nikon 17-35mm at 21mm / f5.6 (corner) Canon 17-40mm at 21mm / f5.6 (corner) Zeiss Contax 21mm at f5.6 (corner)
3.9 points
3.8 points
4.5 points

In common with most Nikon wide angles, the 17-35mm AFS f2.8 really ramps up the corner resolution from f5.6 on; you don’t buy a wide Nikon for its wide aperture performance. This capture is quite respectable, though some way off the delicious rendition of the Zeiss.