Data sheet: Nikkor Ai 28 mm f/2.8

Pekka Buttler, 08/2022 (updated 03/2023)

Specifications

The table below summarizes the lens’ key specifications (measurements based on pictured sample):

Brand:	Nikon (Nikkor)	Lens name	28 mm 1:2.8
Focal length 1	28 mm	Angle-of-view 2	74°
Maximum Aperture	f/2.8	In Production	1977–1981
Lens mount	Nikon F	Subfamily (if applicable)	Ai (Automatic indexing)
Length 3	44,5 mm	Diameter 4	63,5 mm
Filter ring diameter	52 mm	Weight	241
Lens element count	7	Lens group count	7
Aperture blades (S/R/C)5	7 S	Focus throw	190 °
Minimum focusing distance	30 cms	Maximum magnification	1:7,5
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Automatic	Aperture click stops 6	2.8-4-5.6-8-11-16-22

Further notes:
• While similar-spec Nikkor Ai and Ai-s lenses in most cases are very similar, this is one of the exceptions, as the later Nikkor Ai-s 28 mm f/2.8 (data sheet here) is a redesigned version with higher element count and CRC.

A brief genealogy of Nikon SLR lens types

Nikon is undoubtedly one of the great names in 35 mm SLR photography. The Nikon F mount has been in continuous production since 1959. During that time, the mount has developed/changed in some detail, however without ever fully sacrificing compatibility.

In short (a longer version is here), the development of Nikon’s SLR lenses can be traced as follows:
• 1959–1977: Pre-Ai. Manual focus lenses that use ‘rabbit ears’ to communicate selected aperture with the camera body.
• 1977–1986: Ai and Ai-s. Manual focus lenses that may have ‘rabbit ears’ for backward compatibility, but are designed to communicate selected aperture with the camera body through indentations in base of aperture control ring.
• 1986–today: AF and AF-D. Autofocus lenses that do not have a focusing motor within the lens, but rely on the focus motor within the camera. All AF and AF-D lenses are simultaneously Ai-s lenses (they are Ai-s lenses extended with AF) ⁷
• 1996–today AF-S and AF-P. Autofocus lenses that have an internal focusing motor and do not rely on the body having a focusing motor.

The table below

While Nikon has a long history of producing 28 mm f/3.5 lenses (starting in 1960), and has produced 28 mm f/2 lenses since 1970, the intermediate f/2.8 version was first introduced in 1974 (as a new Nikkor lens). The development of Nikkor’s 28 mm f/2.8 designs is summarised in the table below:

years	Series	optical construction	aperture blades	MFD	notes, links
1974–1977	K	7 elements in 7 groups	7, straight	0,3 m	Pre-Ai, rubber focus ring
1977–1981	Ai	7 elements in 7 groups	7, straight	0,3 m	[this lens]
1979–1981	series E	5 elements in 5 groups	7, straight	0,3 m	all-black design
1981–1985	series E	5 elements in 5 groups	7, straight	0,3 m	silver-ring design [data sheet]
1981–2020	Ai-s	8 elements in 8 groups	7, straight	0,2 m	CRC [data sheet]
1986–1990	AF	5 elements in 5 groups	7, straight	0,3 m	plastic focus ring
1990–1994	AF new	5 elements in 5 groups	7, straight	0,3 m	rubber focus ring
1994–2020	AF-D	6 elements in 6 groups	7, straight	0,25 m	[data sheet]

Adapting

Besides adapting, this lens can be used natively on all current high-end Nikon dSLRs and several earlier medium-to-high-end older Nikon dSLRs ⁸. Likewise, if it still has its rabbit ears, it can be natively used on all Nikon F-mount film cameras ever produced (without the rabbit ears, it is limited to post 1977 bodies).

Thanks to being a fully manual lens (manual aperture, manual focus), the lens can be adapted to all mirrorless cameras using a suitable dumb adapter (and such adapters are easy to find). Moreover, a large range of special adapters (helicoid adapters, tilt/shift adapters, speed boosters) for using Nikon F lenses on most mirrorless systems are available.

Using Nikon F lenses on non-Nikon SLRs and dSLRs is likewise a distinct possibility. Thanks to the relatively generous flange focal distance of the Nikon F mount (46,5 mm), adapter rings for all dSLR mounts are available as well as for a goodly portion of film-era SLR mounts. Such rings may not allow for auto aperture, but even then the lenses can be used in stop-down metering mode.

Footnotes

1. Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
2. Picture angle is given in degrees and concerns the diagonal picture angle. Rule of thumb:
   > 90 ° ==> Ultra-wide-angle
   70–90 ° ==> Wide-angle
   50–70 ° ==> Moderate wide-angle
   40–50 ° ==> ‘Standard’ or ‘normal’ lens
   20–40 ° ==> Short tele lens
   10-20 ° ==> Tele lens
   5-10 ° ==> Long tele lens
   < 5 ° ==> Ultra-tele lens ↩︎
3. Length is given from the mount flange to the front of lens at infinity. ↩︎
4. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
5. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
6. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click.a ↩︎
7. There is a further sub-class of AF-D lenses called AF-I lenses that are otherwise AF-D lenses (meaning, fully Ai-s compatible), but have an internal focus motor. Only long tele lenses were made in AF-I variants. ↩︎
8. As of this writing, the following Nikon dSLRs fully support Aperture priority and manual metered modes on Nikkor Ai lenses: D2, D3, D4, D5, D6, D200, D300, D300s, D500, D600, D610, D700, D750, D780, D800, D800E, D810, D850, D7000, D7100, D7200. ↩︎