New NIKKOR Lens Discovered! NHS-62, Dec 98
by Mike Symons with photos by Tony Hurst
(abridged)

An extremely unusual 5cm/f2.0 Nikkor. First, here are the specifics of this fascinating lens;

1. It is a rigid 5cm/f2.0, serial #53422. The number indicates its vintage, as it was manufactured before Nippon Kogaku began their date reference numbering (approx. June 1944).
2. The glass surfaces are uncoated.
3. There are two small serrated "tabs" on the outer ring to adjust the aperture (Fig.1).
4. The lens stops down to f1l, rather than the normal f16. Most members will recall that only 2 other known Nikkors have this unorthodox trait; the 1950 5cm/ft.5 Nikkor-S, and the much earlier (and extremely rare) 5cm/ f2.0 Regno-Nikkor lens used in conjunction with the WWII Seiki Kogaku (Canon) X-Ray Camera.
5. It has the older European method of engraving; i.e., the f2.8 & f5.6 are shown as f2,8 & f5,6. The comma was used in place of the period.
6. Again, the European method of "Nr." rather than "No." in front of the serial number.
7. There is a wide single knurled ring on the barrel. All other Nikkor normal lenses have 2 knurled rings (Fig. 1).
8. The filter size is also unusual ... 38mm rather than 40.5mm found on many of the early Nikkors, or 39mm found on many early Leica lenses.
9. There is an engraving error as well; "Kogku" rather than "Kogaku". The'a' is missing.
10. The printing font is of an earlier style, and in the word "Nippon", the tails of the two'Ps'are even with the bottom of the line, rather than below it .
11. There is no "Tokyo" or "Japan" engraved on the front ring, another indication of its age.