Data sheet: Nikkor Ai 50 mm f/1.8

Pekka Buttler, 08/2022


The table below summarizes the lens’ key specifications:

Brand:Nikon (Nikkor)Lens name50 mm 1:1.8
Focal length(s)150 mmAngle-of-view246°
Maximum Aperturef/1.8In Production1978–1982
Lens mountNikon FSubfamily (if applicable)Ai (Automatic indexing)
Length337,2 mmDiameter463,4 mm
Filter ring diameter52 mmWeight216 grams
Lens element count6Lens group count5
Aperture blades (S/R/C)57 SFocus throw210 °
Minimum focusing distance45 cmsMaximum magnification1:6,8
Has manual aperture ringYESHas Manual focus ringYES

Further notes:
• This lens is (chronologically) Nikon’s first 50 mm f/1.8 lens. But there were a great many variants to follow.
• This lens was – for a short while – produced in parallel with the last (Ai) version of Nikon’s venerable 50 mm f/2 lens.
• This lens is easy to distinguish from a plethora of other Nikon 50 mm f/1.8 lenses in that it is the only one to lack the Ai-s notch on the flange.
• Should a lens hood be needed, Nikon’s dedicated offering are the HR-1 (rubber) HS-11 (steel) hoods.

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) 6
• 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.

What camera manufacturer would not have a nifty fifty in their line-up? Interestingly, from the launch of the Nikon F system (1959) ever until the launch of this lens (1978), Nikon’s take on a nifty fifty was a 50 mm f/2 lens (for a run-down of that genealogy, see this data sheet). But with the introduction of this lens in 1978, Nikon upped its nifty fifty to f/1.8, thus gaining parity with most of the industry.

During the following decades a great many variants have been produced. To add some potential for confusion to the mix, some models were made for export markets, other for Japanese domestic markets. There was also a variants that clearly aimed for the ‘pancake’ mould. For a chronological summary of Nikon’s 50 mm f/1.8’s see below:
• 1978-1982 (Ai): 6 elements, 5 groups; 7 straight blades; 0,45 m MFD (this lens)
• 1979–1981 (E): 6 elements, 5 groups; 7 straight blades; 0,6 m MFD, pancake (all-black design)
• 1980–1982 (Ai-s): 6 elements, 5 groups; 7 straight blades; 0,45 m MFD, pancake, (for Japanese market)
• 1981–1985 (E): 6 elements, 5 groups; 7 straight blades; 0,6 m MFD, pancake (silver ring design) [data sheet]
• 1981–1985 (Ai-s): 6 elements, 5 groups; 7 straight blades; 0,45 m MFD, (for Export market)
• 1985–2005 (Ai-s new): 6 elements, 5 groups; 7 straight blades; 0,6 m MFD, pancake (plastic focus ring) [data sheet]
• 1986-1990 (AF): 6 elements, 5 groups; 7 straight blades; 0,45 m MFD (plastic focus ring) [data sheet]
• 1990-2001 (AF new): 6 elements, 5 groups; 7 straight blades; 0,45 m MFD (rubber focus ring)
• 2002-today (AF-D): 6 elements, 5 groups; 7 straight blades; 0,45 m MFD (new barrel design) [data sheet]
• 2011–today (AF-S; G): 7 elements, 6 groups, 7 rounded blades; 0,45 m MFD
• 2018–today (Z): 12 elements in 9 groups, 9 rounded blades; 0,4 m MFD


Besides adapting, this lens can be used natively on all current high-end Nikon dSLRs and several earlier medium-to-high-end older Nikon dSLRs7. 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.


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 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.

7 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