Nikkor 10.5cm/105mm F2.5
Arguably this is Nikon's longest lived and most highly successful lens formulation family. It can be claimed that in its very first embodiment, it was not actually a 105mm(10.5cm) F2.5 but rather its direct ancestor, the 8.5cm F2.0 that first appeared April 1949 for the Leica/Contax/Nikon complex of rangefinder camera bodies.
The evolutionary step from the 8.5cm F2.0 to the 10.5 F2.5 lens (introduced 1954) is obvious when the lens formulas and physical layouts are compared. The elements and their layouts are almost identical except for scale and the F2.5 has its outer radial dimension cut back somewhat. This was done no doubt for a variety of reasons (economy of production, ease of carrying...etc.) but it was a very fortuitous step, since even though the 8.5cm lens is outstanding in performance for its time, the derived 10.5cm F2.5 was better in every measurable respect. It was so good that from the time that it premiered as a part of the Nikon F's initial line up in early 1959 to the introduction of the 105mm F2.8 Micro Nikkor in April 1984 it reigned supreme, with only the subtlest of modifications, as the sharpest lens in that part of Nikon's array.
Version One: Only about 500 of these are known to have been manufactured. Onset serial number 120102. Tick markings on both the distance and aperture scale. A red "R" marking the infrared focus offset or shift. Nine paerture blades Textured chrome filter ring. Blue lens coating. F stops to F=22. No bolt heads in mount. Lens data in cm. NKJ designation.
Version Two: Serial numbers from about 124000 . Six aperture blades. Coating changed from deep blue to amber. No "Tick Marks". Red "R" has evolved to just a red dot. Earliest examples display "PAT. PEND." and "LMIJ" on the textured chrome body near the grip ring.
Later versions drop "PAT. PEND." and migrate the "slant M" LMIJ to the focus ring (slant M is to go eventually in favor of vertical M as well):
Version Three: To approximate SN 254000. Five "blade" bolt heads appear in mount surface. LMIJ with vertical sides "M" migrates to focus ring.
Version Four: SNs 407301 to 473834, Long scalloped focus grip.
Version Five: 1973 (SNs 500001 to 571564) Optical formula went from 5/3 to 5/4. A similar but updated formula. Coating went to NIC. Minimum Aperture went to F32. Color scheme of lens changed to almost entirely satin black except for the chrome grip ring. Minimum focus distance dropped to under 3.3ft (1m).
Version Six: May 1975 Virtually identical to Version Five but incorporates Nikon's new RIFR look. SN onset 673101
Version Seven: AI conversion 1977 (SN onset 740001) Highly similar to Version Six but with one other deviation. Minimum aperture is F22 once again.
Version Eight: 1981 (SN onset 890001) AIS version.
