Head to head
Which is the best lens for capturing ultra-wide images? We pit a fisheye against a zoom
Nikon AF DX 10.5mm f/2.8G ED fisheye
Although it's designed for DX format D-SLRs this lens can be called a full-frame or diagonal fisheye. That’s because, unlike with circular fisheye lenses, the image circle it produces covers the whole of the image sensor, rather than just a central, circular region.
Like other diagonal fisheyes, this delivers an immense viewing angle of 180 degrees on the diagonal of the frame. That’s pretty astonishing, but less than the viewing angle of a circular fisheye, which is 180 degrees in both the horizontal and vertical planes.
Part of the attraction of a curvilinear lens is that it produces massive barrel distortion, which gives images their unique fisheye look. It can be a useful creative tool, but the attraction can soon wear thin for landscape and architectural photography.
Autofocus in this lens is driven from a motor in the camera body, via a screw mechanism in the mounting plate. This makes autofocus impossible with D3XXX- and D5XXX-series cameras, and other entry-level D-SLRs that don’t have a built-in AF motor.
The depth of field in this and other fisheye lenses is so enormous that you can keep close foreground objects and the distant horizon sharp simultaneously, even at wide apertures. Accurate focusing is largely unnecessary, so in fact cameras without AF are fine.
Sigma 8-16mm f/4.5-5.6 DC HSM
Whereas fisheyes are curvilinear optics, this Sigma is a rectilinear lens that aims to keep distortions to a minimum. Even so, it has the shortest focal length of any rectilinear zoom lens for Nikon D-SLRs, and correspondingly has the widest available viewing angle.
Even at its widest zoom setting, the Sigma loses out to the Nikon, with a maximum viewing angle of 'just' 121 degrees on the diagonal. But that’s noticeably more than on most ultra-wide zooms – the Nikon 10-24mm has a maximum viewing angle of 109 degrees.
Despite its extended maximum viewing angle, the Sigma produces less barrel distortion at its widest zoom setting than the Nikon 10-24mm rectilinear zoom lens, and there’s barely any distortion whatsoever towards the long end of the zoom range.
The Sigma lens has a ring-type ultrasonic autofocus system that is both rapid and whisper-quiet. It can autofocus on any Nikon D-SLR body, and comes complete with the usual provision of full-time manual override in Single AF mode.
It’s no match for a fisheye, but depth of field is still impressive. The hyperfocal distance at the widest zoom setting and an aperture of f/8 is 40cm, so everything from 20cm (measured from the focal plane near the rear of the camera) to infinity will be in focus.