Data Sheet: Nikkor K 50 mm f/2

Pekka Buttler, 09/2022

Specifications

The table below summarizes the lens’ key specifications:

Brand:	Nikon (Nikkor)	Lens name	50mm 1:2
Focal length 1	50 mm	Angle-of-view 2	46°
Maximum Aperture	f/2	In Production	1974–1977
Lens mount	Nikon F	Subfamily (if applicable)	Pre-Ai (F-type)
Length 3	42,3 mm	Diameter 4	63,6 mm
Filter ring diameter	52 mm	Weight	218 grams
Lens element count	6	Lens group count	4
Aperture blades (S/R/C) 5	6 S	Focus throw	180 °
Minimum focusing distance	45 cms	Maximum magnification	1:6,7
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Automatic	Aperture click stops 6	2-2.8-4-5.6-8-11-16

Further notes:
• Nikon introduced its first 50 mm f/1.8 in 1978 (almost 20 years after the introduction of the Nikon F). Until then, the 50 mm f/2 was Nikkor’s more pedestrian standard lens.
• While this lens harkens back to the time before Nikon decided to have uneven numbers of aperture blades on all their lenses, the 50/2 continued having 6 blades until the end of manufacture.
• Nikon has offered Ai for all K-type 50/2’s.
• Nikon offered two alternative dedicated lens hoods for this lens: the HN-5, HS-6 and HR-1. All are mounted on the filter threads.

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. Pre-Ai lenses can further be subdivided into
• F-type (1959–early 1970s: metal focus ring and single-coated),
• C-type (early 1970s–mid 1970s: metal focus ring and multicoated), and
• K-type (mid 1970s to 1977: rubber focus ring and multicoated).
A significant share of remaining Pre-Ai lenses have since been converted to Ai-spec (Ai’d)
• 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.

Nikon offered a nifty fifty with an f/2 maximum aperture from the 1959 launch of the Nikon F system until 1979. During that time, relatively minor changes were done:
• 1959–1963 5 cm f/2 (7 elements in 5 groups, 6 or 9 blades, 0,6 m MFD, “Nippon Kogaku”) (F-type)
• 1964–1967 50 mm f/2 (6 elements in 4 groups, 6 blades, 0,6 m MFD, “Nippon Kogaku”) (F-type)
• 1967–1972 50 mm f/2 (6 elements in 4 groups, 6 blades, 0,6 m MFD, “Nippon Kogaku” and “Nikon) (F-type) [data sheet]
• 1972–1974 50 mm f/2 (6 elements in 4 groups, 6 blades, 0,6 m MFD) (C-type)
• 1974–1977 50 mm f/2 (6 elements in 4 groups, 6 blades, 0,45 m MFD) (K-type) (this lens)
• 1977–1979 50 mm f/2 (6 elements in 4 groups, 6 blades, 0,45 m MFD) (Ai)

Adapting

There are good chances this lens can still be used natively:
• If the lens has been AI’d, this lens can be used natively on all current high-end Nikon dSLRs and several earlier medium-to-high-end older Nikon dSLRs ⁸ as well as all post-1977 Nikon Film cameras.
• If it is in its original Pre-Ai form, it can be used natively on the Nikon Df and on all Nikon F-mount film cameras produced before 1977.

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. ↩︎
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. ↩︎