Best prime lenses for Nikons: 8 tested

Sigma 28mm f/1.8 EX DG - £345/$450

The Sigma 28mm is designed first and foremost as a fast, wide-angle prime lens for full-frame cameras. As such, it's a big, heavy optic - the largest in the group by quite a margin. The lack of an internal autofocus motor isn't too much of a drawback, as all full-frame Nikon DSLRs have a screw drive for actuating autofocus directly from the camera body.

With an effective focal length of 42mm on APS-C format cameras, there's also the temptation to use this as a 'standard' prime lens on DX bodies. However, size and weight make the Sigma 28mm less than ideal. The camera-driven autofocus is a bit sluggish, but sharpness is great even at the maximum aperture of f/1.8.

This lens is a good choice for indoor, handheld shooting, with wide-angle potential on a full-frame body. However, there's noticeable vignetting at f/1.8, although this disappears at smaller apertures or when you use the lens on an APS-C format camera. Barrel distortion is noticeable and rather worse than that displayed by many of the other lenses in the group.

Sharpness

Best prime lenses for Nikons: 8 tested

Sharpness is both impressive and consistent throughout the aperture range, only dropping off at f/16 to f/22.

Lab test
Sharpness at f/2.8: 1905
Sharpness at f/8: 1920
Sharpness at f/16: 1691

Fringing

Best prime lenses for Nikons: 8 tested

Chromatic aberration is well contained, making the Sigma 28mm a good choice for landscape shoots on full-frame cameras.

Lab test
Fringing at f/2.8: 0.19
Fringing at f/8: 0.26
Fringing at f/16: 0.21

Distortion

Best prime lenses for Nikons: 8 tested

The second-worst lens on test in terms of distortion, there's a clear barrel effect. However, it's still better than most zooms.

Distortion: -1.12

Image test verdict

Best prime lenses for Nikons: 8 tested

Apart from some noticeable barrel distortion, the Sigma 28mm is optically very good, and is well suited to full-frame use.