Medical-Nikkor 120mm f/4 IF

Nikon’s Instruments Division sold microscopes to hospitals, and hospitals asked it for something else: a way to record an operation, or a mouth, or a research specimen, accurately and without a photographer getting in the way. The answer was the Medical-Nikkor Auto 200mm f/5.6, drawn for trial production in January 1962, in mass production by May and on sale that December — four elements in four groups, conceived when the Nikon F was three years old and the 43-86mm zoom did not yet exist. It was revised twice, cosmetically in 1972 and for multicoating in 1974, and it stayed on the price list for seventeen years.

The replacement was assigned to Iizuka Yutaka, who had been designing a telephoto zoom immediately before it, and the lens shows where his head was. What he built is a convex-concave-convex arrangement in the shape of a telephoto zoom’s master group, with the concave group doing the focusing the way an internal-focusing super-telephoto does — a zoom’s variator repurposed to change magnification without moving the front of the lens. The mechanics of magnification by zooming and magnification by focusing are nearly the same problem; the difference is whether the distance from subject to film is allowed to change. Sato, who tells the story, notes drily that anyone who looks at the cross-section and sees a telephoto zoom is paying attention.

The focal length was not the first choice. Records show trial drawings issued in 1979 with the length changed from 105mm to 120mm, and Iizuka, asked about it years later, could only say that 120mm gave the right working distance. That is the constraint the whole lens is built around. It focuses from 1.6m down to 0.35m for ratios from 1:11 to life size, and from 0.33m to 0.26m with the 2× attachment screwed on, and all of those distances are long enough to keep the camera out of the surgeon’s way.

Almost nothing about the lens is under the photographer’s control, and that is deliberate. The ringlight is built into the front and fires at a fixed guide number; once the film speed is set on the ASA/ISO ring, the diaphragm is geared to the focusing ring, so the aperture is whatever the reproduction ratio requires — f/4 at 1:11, f/32 at life size, f/32 throughout with the attachment fitted. A green LED and a miniature optical system inside the barrel throw the reproduction ratio into the bottom right of the viewfinder, where it doubles as the flash ready-light, and print it onto the film at the instant of exposure. A 12V lamp at the front lights the subject for sixteen seconds so the focus can be found. Power comes from an LA-2 mains unit or an LD-2 pack of eight AA cells, through a four-pin socket, and without one of them the lens does not meter, does not flash and does not imprint.

There was one version and it never changed: 23,220 lenses in a single serial block, by Vink’s arithmetic, against at least 19,217 across the six blocks of the 200mm that preceded it — one of those six carries no quantity, so the older lens’s total is unknown and may be the larger of the two. What is unresolved is when it went on sale. Nikon’s own account is specific — December 1981, the last days of the year — while Vink’s block opens in February 1981, ten months earlier, and neither party explains the other. Beyond that the record is thin in the ordinary ways: no factory production figure, no published price, no discontinued-product page, and two different picture angles in print for the same piece of glass.