Lens Test: Nikon 20mm f/2.8D AF
A fast, remarkably compact ultrawide-angle for Nikon fans.
What you should know: If any optic in Nikon’s extensive lens line can be called a standard ultrawide, it’s the long-running 20mm f/2.8D AF Nikkor. Covering an impressive 94- degree angle, it’s also pleasantly compact and fast enough for available-light shooting. We were surprised we hadn’t already tested it, so here it is.
Hands on: Very well-finished in satin black, this lens is average in weight and surprisingly compact for a 20mm f/2.8. The reasonably wide, ribbed, rubberized manual-focusing ring turns very smoothly with a well-damped action. Distance scales under a Plexiglas window are smallish but legible (feet in yellow and meters in white-on-black). The adjacent depth-of-field scale includes an IR-focusing index, but only covers apertures of f/5.6 and f/11. The aperture ring has detents at whole-stop intervals, large, legible numerals, and a tab to lock the aperture at f/22 when using program- or shutterpriority autoexposure.
In the lab: SQF data indicate excellent performance. There is minimal barrel distortion (0.45 percent). Exposure accuracy at the film plane was good, with 1⁄3-stop underexposure at maximum aperture due to light falloff, less than 1⁄3-stop under from f/4 to f/16, and about 2⁄5-stop under at f/22. These are considerably better-than-average figures for an ultrawide-angle lens.
At the closest focusing distance of 10 inches (1:8.6), center sharpness was excellent at all apertures. Corner sharpness was acceptable at f/2.8, good at f/4, very good at f/5.6, excellent from f/8 to f/16, and very good at f/22. Optimum close-up performance was at f/1l.
In the field: Test slides were sharp and contrasty from center to corners at all apertures and distances. Light falloff was gone by f/5.6. Flare was very well-controlled at all apertures, with no ghosting visible-an excellent result. Autofocus timing was fast and AF was moderately quiet.
Conclusion: An outstanding ultrawide-angle lens that delivers pro-caliber performance at a price within the range of many Nikon enthusiasts.
20mm (20.42mm tested), f/2.8 (f/2.87 tested), 12 elements in 9 groups. Focusing turns 100 degrees clockwise.
Diagonal View Angle: 94 degrees.
Weight: .58 lb.
Filter size: 62mm.
Mount: Nikon AF.
List price: $670.
Street price: Approx. $490.