Sankyo-Kohki Komura 80mm f/1.8

Sankyo-Kohki Komura 80mm f/1.8

Among the fast short telephotos that Japanese third-party makers built for rangefinder bodies in the 1950s, the Komura 80mm f/1.8 stands out for its unusual optical layout. Rather than following the Sonnar pattern used by many contemporary fast Japanese portrait lenses, its five-element, four-group arrangement is generally identified as an Ernostar-derived design, which collectors note gives it a rendering distinct from the Sonnar-type Nikkors of the same period [4]. It was sold by Sankyo Kohki under the Komura brand, a name the company assembled from the surnames of its president and managing director [1].

The lens is a Leica thread mount (LTM, M39) optic and is coupled to the rangefinder, so it can be focused through the camera's rangefinder patch rather than by scale estimation alone. The fast f/1.8 maximum aperture and roughly 80mm focal length suit it to head-and-shoulders portraiture, where its twelve-blade diaphragm produces a nearly circular aperture opening across a wide range of settings. It focuses to about 1.25 m, takes 48 mm front filters, and is most often seen in a two-tone black and chrome barrel [3]. Komura also produced an 80mm f/1.8 in the Nikon rangefinder mount and in reflex mounts such as Exakta, so buyers should confirm the mount of a given example [4].

Sankyo Kohki branded its English-language products as "Sankyo Kohki" or "Sankyo Koki," and lenses are commonly engraved "Sankyo Koki Tokyo Komura." The company built lenses across many systems, and surviving Komura optics turn up in a wide range of mounts, which can complicate identification of any single barrel.

Optical qualities

Rendering Documented information specific to this lens is limited, but its character follows from its design and era. The Ernostar-type formula is reported to give it a distinctive out-of-focus rendering, noticeably different from the Sonnar-type fast telephotos it competed against [4]. More broadly, modern collectors describe Komura's fast lenses as delivering good contrast, pleasing color, and smooth bokeh [2]. As a single-coated lens from the 1950s used wide open at f/1.8, it can be expected to show the lower contrast and flare sensitivity typical of uncoated-to-single-coated optics of the period, though detailed test data is not widely published.

History

Development and Launch The Komura brand belonged to Sankyo Kohki Co., Ltd., a Japanese optical firm established in July 1951 as the Sankyo Optical Research Institute and reorganized under the Sankyo Kohki name in 1955 [1]. The Komura trademark itself was formed from characters in the names of company president Mitsuru Kojima and managing director Inamura [1]. The firm's earliest products were sold under the Chibanon (also spelled Chivanon) name and included enlarging lenses and optics for early Japanese folding cameras [3]. As the company grew it moved into interchangeable lenses for rangefinders and SLRs, with the Leica thread mount and Nikon rangefinder mount being the most common; this expansion took place while German cameras still dominated and Japanese optics were gaining international recognition [3]. The 80mm f/1.8 belongs to this rangefinder-era output of fast Komura lenses.

Production Evolution Sankyo Kohki registered the Komura trademark in the United States in 1962, with first use cited as 1953 [5]. The company later renamed itself Komura Lens MFG. Ltd. in July 1969 and continued until bankruptcy in 1980 [1]. Over its life it produced lenses for many systems, including Contax, Exakta, Leica, and Nikon mounts, and it developed an interchangeable Unimount (Unidapter) adapter system in the 1970s to fit a single lens to several reflex bodies [1].

Special editions No widely documented factory special editions of the Komura 80mm f/1.8 are recorded. The lens was produced in different mounts for different systems, but no rare commemorative or military variant of the rangefinder version is established in the sources reviewed here.

Collector Notes Because Sankyo Kohki made the 80mm f/1.8 in more than one mount, confirm that an example is the rangefinder-coupled LTM version rather than a reflex (Exakta) or Nikon rangefinder lens before buying [4]. Engravings typically read "Sankyo Koki Tokyo Komura." As with most lenses of this age, check the glass for haze, separation, and coating wear, since older Komura optics are noted to be prone to fogging on internal elements [1]. Verify originality of the two-tone finish and confirm the 48 mm filter thread when sourcing caps, hoods, or filters [3].

Sources

• [1] Kameramanufaktur. Sankyo Kohki and the Komura lenses. https://kameramanufaktur.jimdofree.com/lenses/komura-lenses/
• [2] Camerapedia (Fandom). Sankyō Kōki. https://camerapedia.fandom.com/wiki/Sanky%C5%8D_K%C5%8Dki
• [3] Mike Eckman. Sankyo Kohki Komura 500mm f/7. https://mikeeckman.com/2022/10/sankyo-kohki-komura-500mm-f-7/
• [4] Rangefinderforum. Komura 80mm f1.8 by Sankyo Kohki for Nikon RF. https://rangefinderforum.com/threads/komura-80mm-f1-8-by-sankyo-kohki-for-nikon-rf.4752270/
• [5] Crafting Pixels. vintage lens. https://pixelcraft.photo.blog/tag/vintage-lens/