Tokyo Kogaku Topcor-S 5cm f/2

Tokyo Kogaku Topcor-S 5cm f/2 LTM

The Tokyo Kogaku Topcor-S 5cm f/2 LTM is a Japanese Leica screw-mount standard lens made for Leotax and other L39 rangefinder cameras. Tokyo Kogaku, later known internationally as Topcon, was one of Japan’s important postwar optical manufacturers, and its Leica thread-mount lenses are generally regarded as uncommon, well-made collector lenses [1]. The 5cm f/2 was sold as a normal lens option with Leotax rangefinder cameras during the 1950s and early 1960s [2].

The lens uses a 6-element, 4-group double-Gauss optical design, with collector sources often describing the Topcor-S 5cm f/2 as a Biotar-type normal lens [1][3]. It has a Leica screw mount, rangefinder coupling, 40.5 mm filter thread, manual aperture control, and a focusing lever. LegacyCamera measured one later black-finish example at 255 g, with a 41 mm extension from the camera body at infinity focus, while Lens DB records the Panda variant at 280 g and 10 diaphragm blades [2][4]. Because barrel material and finish changed across variants, weight and handling can vary by version.

For LeicaLensList, this entry should be kept separate from the Topcor 5cm f/1.5, Topcor 5cm f/1.8, Topcor 5cm f/2.8, State / Simlar / Topcor 5cm f/3.5, and fixed-lens Topcon rangefinder camera lenses. The Topcor-S 5cm f/2 is especially relevant to Leica-compatible collecting because it combines LTM compatibility, Leotax system history, multiple distinctive finish variants, and a less common Japanese alternative to Canon, Nikon, and Leitz 50mm lenses of the same period [1][2][3].

History

Development and Launch

Tokyo Kogaku produced Leica L39 lenses before and after the Second World War, later expanding its postwar rangefinder lens production in cooperation with Leotax cameras [1]. The Topcor-S 5cm f/2 appears in Leotax-era references from about 1954 and was available on Leotax F, T, K, FV, TV2, and T 2L models according to the Leica Copies reference cited by LegacyCamera [2]. Lens DB also places the plain Topcor 50mm f/2 LSM around 1954, with later Topcor-S variants documented from 1957 and 1958 [4].

Production Evolution

Collector sources describe several external generations of the Topcor 5cm f/2 L39 lens. L39camera notes three main exterior versions, with the first generation in chrome-finished brass, a rare intermediate version, and a later version with black aperture and focusing rings and more aluminium components [1]. RangefinderForum separates the Topcor-S 5cm f/2 into all-chrome, Panda, and black/silver aluminium variants, with documented serial examples suggesting all-chrome production around the 210034 to 218847 range, Panda examples around 217984 to 220100, and black/silver examples around 540253 to 552843 [3].

Special Variants

The main known variants are the all-chrome Topcor-S 5cm f/2, the Panda version, and the later black/silver aluminium version [3]. The all-chrome version is usually associated with heavier chrome-over-brass construction, the Panda version uses a similar body style with contrasting finish, and the later black/silver version has a redesigned aluminium barrel and shorter focusing throw [3]. Some collector discussion also distinguishes an earlier plain Topcor version before the Topcor-S engraving became standard [1].

Collector Notes

Collectors should verify the exact front-ring engraving, serial number, barrel type, finish, focusing lever, aperture ring style, filter thread, rangefinder coupling, and close-focus scale. Later versions commonly focus to 1 m, while early Type 1 Lens DB references list 3.5 ft, so close-focus distance should be checked on the actual copy [3][4]. The Topcor-S 5cm f/2 should not be confused with the Topcor 5cm f/1.5, 5cm f/1.8, or 5cm f/2.8 LTM lenses. Common condition checks include internal haze, cleaning marks, coating wear, oil on aperture blades, stiff helicoid grease, missing focusing-lever parts, and mixed or converted barrels.

Sources

• [1] L39camera. 紅塵緣影, Tokyo Kogaku Topcor L39 Standard Lens Series. https://l39camera.com/%E7%B4%85%E5%A1%B5%E7%B7%A3%E5%BD%B1-tokyo-kogaku-topcor-l39%E7%B3%BB%E5%88%97/
• [2] LegacyCamera. The Topcor-S 5cm F2 for Leica Thread Mount. https://legacycamera.wordpress.com/2012/05/12/the-topcor-s-5cm-f2-for-leica-thread-mount/
• [3] RangefinderForum. Topcor LTM Lens Compendium. https://rangefinderforum.com/threads/topcor-ltm-lens-compendium.4816236/
• [4] Lens DB. Tokyo Kogaku Topcor-S 50mm F/2 LSM. https://lens-db.com/tokyo-kogaku-topcor-s-50mm-f2-panda-lsm-1957/