Pekka Buttler, 12/2022
The table below summarizes the lens’ key specifications (measurements based on pictured sample):
|Brand:||Nikon||Lens name||NIKKOR 105mm 1:2.5|
|Focal length(s)1||105 mm||Angle-of-view2||23°20|
|Maximum Aperture||f/2.5||In Production||1977-1981|
|Lens mount||Nikon F||Subfamily (if applicable)||Ai-type|
|Length3||68,9 mm||Diameter4||66,0 mm|
|Filter ring diameter||52 mm||Weight||423 grams|
|Lens element count||5||Lens group count||4|
|Aperture blades (S/R/C)5||7 R||Focus throw||170 °|
|Minimum focusing distance||1,0 m||Maximum magnification||1:7,7|
|Has manual aperture ring||YES||Has Manual focus ring||YES|
• This Ai version replaced the outwardly and optically very similar K-type in 1977 and was, in turn, replaced by the Ai-s variant in 1981. During that time 150 000 copies were made.
• Altogether, Nikon manufactured more than half a million of the 105/2.5 (Gauss)
• The Ai-version is the 2nd to last version of this Nikkor classic, and the last one to need a separate hood.
• My sample looks outwardly as if it had been to Afghanistan, but the optics are pristine.
• Nikon offered a dedicated lens hood: the HS-8, a filter thread mounted, snap on steel hood.
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) 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.
Throughout the 1960’s and 1970’s Nikon’s main emphasis in short tele lenses was on the various designs of 105 mm f/2.5 lenses. The development of these is summarised below:
• 1959–1971 105mm f/2.5 (5 elements in 3 groups, 6(9) blades, 1,2 m MFD, “Nippon Kogaku Nikkor-P”) (F-type) [data sheet]
• 1971–1973 105mm f/2.5 (5 elements in 4 groups, 7 blades, 1 m MFD, “Nikon Nikkor-P”) (F-type)
• 1973–1975 105 mm f/2.5 (5 elements in 4 groups, 7 blades, 1 m MFD, “Nikon Nikkor-P•C”) (C-type)
• 1975–1977 105 mm f/2.5 (5 elements in 4 groups, 7 blades, 1 m MFD, rubber focus ring) (K-type)
• 1977–1981 105 mm f/2.5 (5 elements in 4 groups, 7 blades, 1 m MFD, rubber focus ring) (Ai-type) [this lens]
• 1981–2005 105 mm f/2.5 (5 elements in 4 groups, 7 blades, 1 m MFD, rubber focus ring) (Ai-s-type)
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