Tessar 13.5cm f/4.5 (HK 7)

The slower of the two 13.5cm lenses for the HK 7 — the same focal length as the standard Biotessar at about a stop and a half less speed, and presumably the cheaper or more available of the pair in wartime.

Ross Aktiebolag of Göteborg was the company Victor Hasselblad ran through the war, building aerial cameras for the Swedish air force, and it is where the firm that later made the 1600F learned its trade. Ross built the bodies and, unusually, the shutters; it made no glass at all. The lenses came from Germany — Zeiss, Schneider and Hugo Meyer — and Hasselblad Historical notes that no documentation has been found describing how they were imported into a neutral country that badly needed optics and rather more badly needed to be left alone.

A Tessar of this focal length and aperture was among the most ordinary lenses in Europe in 1941, made by Zeiss in enormous numbers for plate and press cameras, which is likely why it appears here: a neutral country buying optics through an uncertain supply chain takes what it can get in quantity. Nothing Ross fitted was anti-reflection coated; coating reached Swedish military optics after the war, and these lenses date from before it.

One habit of the Ross shop matters to anyone who finds one of these lenses loose. The mounts were hand-tuned to fit a particular camera, and the protective barrel was then engraved with that camera’s serial number. A lens from one body will not necessarily seat correctly on another of the same model, which is why these are worth far more still attached to the camera they were fitted to than separated from it.

Hasselblad Historical’s account of the Ross cameras is the only substantial source on them, and its author marks several specifications as information requested — an open call to readers for detail he does not have. Maximum aperture, weight, element count and production quantities for this lens are among the figures that no published source gives, so what is recorded here is deliberately short. The aperture recorded here follows the secondary listings of the HK 7’s lens set rather than Hasselblad Historical’s own page, which names the Biotessar as the standard lens without tabulating the alternatives.