Nikon 20mm f/2.8 [AI-S]
This lens features Nikon's CRC (Close Range Correction). On FX, wide open, this lens has some corner softness and vignetting. You need to stop down a few clicks to f/5.6 if you want corner sharpness and no vignetting. This is bad for a lens most people would buy for the f/2.8 maximum aperture. Flare, ghosting and CA is well controlled. On FX, it also has difficult to correct distortions, with barrel distortion in the centre and almost no distortion at the edges.
Mechanical construction is very good, much better than the AF-D version, which is supposed to use the same optical formula.
Unless you don't care about corners, you should let this pass on this on FX. It will perform much better on DX, but then it is not an ultra-wideangle any more.
When used for IR, there is a faint hot-spot.
Used screw-on lens hood HK-14.
Rating: Ed: 47, User: - (normalized, 0=useless, 50=average, 100=excellent).
Mount: Nikon F.
Aperture range: f/2.8 to f/22.
Close focus distance (CFD): 26 cm / 0.85 ft (from sensor plane).
Filter diameter: 62 mm.
L x D, W: 44 x 66 mm, 260 g.
IR: No hotspot reports.
Approximate street price: USD 590 (new, w/o tax).
Nikon is a multinational corporation headquartered in Tokyo, Japan specializing in optics and imaging. Its products include cameras, lenses, flash units, scanners, binoculars, microscopes, measurement instruments, and steppers (used in semiconductor fabrication). The company was founded in 1917 as Nippon Kōgaku Kōgyō Kabushikigaisha (Japan Optical Industries Corporation), and renamed Nikon Corporation, after its cameras, in 1988. Nikon Corporation is one of the companies of the Mitsubishi Group.