Nikkor-T 10.5cm f/4

The Nikkor-T 10.5cm f/4 is the lens Nippon Kogaku wasn’t supposed to make: a three-element budget telephoto from a company whose name rested on premium glass, sold at half the price and half the weight of its own celebrated 10.5cm f/2.5 — and, in Nikon designer-historian Haruo Sato’s (佐藤治夫) telling, probably the first Nikon telephoto designed with the ordinary consumer as its imagined customer. Enthusiasts dubbed it the “Mountain Nikkor” after the Leitz Berg-Elmar, the mountain Elmar, whose slim flaring silhouette it recalls; the nickname was never Nikon’s, but it stuck. The gamble failed in the marketplace — roughly 2,000 were made across its two mounts in about three years before the f/2.5’s popularity finished it off — and failure accomplished what success never could: the cheap Nikkor is now a scarce collector’s piece trading well above lenses that outsold it many times over.

The optics were designed by Zenji Wakimoto (脇本善司) — the same hand behind the utterly different Nikkor-S 8.5cm f/1.5, a pairing Sato offers as proof of his range. The mass-production drawings went out in December 1959, with Exakta and Praktica versions planned alongside the Nikon mounts before both were aborted, and the lens reached the market in spring 1960: the F-mount version dated March, the S-mount release following that spring. That timing made it simultaneously one of the last Nikkors designed for the rangefinder and among the first sold for the F — and it completed Nikon’s budget counterpart to the era’s “three sacred treasures” kit of 35, 50 and 105, joining the 3.5cm f/3.5 and 5cm f/2. Sato frames it as the origin of a house doctrine: a cheap lens reaches the most hands, so it must uphold the quality of the whole Nikkor name — in some ways a harder brief than any flagship.

A triplet is the textbook minimum — the fewest elements that can correct the Seidel aberrations and both chromatic errors at once — and exactly right for a modest-aperture medium telephoto, where the short glass path also buys clean color and tone. Wakimoto tuned it to his signature balance: spherical aberration left slightly overcorrected, so the lens is gently soft wide open and snaps to high-contrast sharpness from half a stop down, reaching near-peak performance by f/5.6 and peaking between f/8 and f/11. Modern users keep rediscovering the same lens — sharp in the focal plane even at f/4, chromatic aberration well controlled, distortion too slight to notice, smooth and undramatic in the out-of-focus areas, genuinely weak only against flare. The design’s completeness had a long afterlife: new optical designers at Nikon have traditionally cut their teeth on precisely this specification, a 105mm f/4 triplet.

The two versions share one serial sequence, observed from 405401 to 411314, with S- and F-mount lenses intermixed throughout — so any quantity computed from a span covers both mounts, and no per-mount production split exists. That span of some 5,900 numbers sits awkwardly against the published total of about 2,000, a tension the record has not resolved. Rotoloni files the lens among the puzzles — a deliberately slow lens released at a late date, from the maker of the sharpest and most popular medium telephoto of the day — and the market agreed at the time: the S version, arriving just as its buyers defected to the F system with the 10.5cm f/2.5 already on the shelf, sold worst of all, and is today the rarer and more expensive of the two.