Simlar
Simlar (シムラー) lenses were made by Tōkyō Kōgaku (predecessor of Topcon) from c.1935 to 1955. The name Simlar (written shimurā in Japanese) is derived from Shimura (志村), a place name in Tokyo where the company plant was located.[1] The Simlar brand was originally used for a four-element lens design, copy of the Tessar. From the late 1930s or early 1940s, the name was applied to all the lenses made by Tōkyō Kōgaku with advanced specifications, as opposed to the Toko or State brands, used for three-element lenses. In 1955, the names Toko and Simlar were replaced by the single brand Topcor.
Contents
Simlar lenses in leaf shutters, for civilian cameras
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| Simlar 10.5cm f/4.5 lens no.25150 on a Luxury Pearl. Picture by eBayer imagemeister. (Image rights) |
Simlar 6cm f/3.5
The Simlar 6cm f/3.5 was mounted on the Minion III, introduced during World War II but mainly sold in the postwar period.
Simlar 7.5cm f/3.5
At least one example of the Simlar 7.5cm f/3.5 was mounted on a Lord by Tōkyō Kōgaku, made c.1937–8, though the camera was normally advertised with a Toko 7.5cm f/3.5 three-element lens.
Simlar 10.5cm f/4.5
The Simlar 10.5cm f/4.5 was offered from c.1935 on the First, Special First, First Etui and First Roll, made by Kuribayashi and distributed by Minagawa. The lens was normally paired with a Seikosha shutter (T, B, 1–250). These cameras were certainly the first equipped with a Simlar.
The same lens was also mounted on the Luxury Pearl and New Lily released in 1937 by Konishiroku, in combination with a Leo shutter, name variant of the Seikōsha.
Simlar interchangeable lenses, for rangefinder cameras
See the main article on Tōkyō Kōgaku lenses in Leica screw mount.
Other Simlar lenses
Regular barrel lenses
The Simlar lens was offered in barrel mount for general use in large-format cameras, both before and after World War II.[2] It is said that various focal lengths were offered.[2] Examples of a 21cm f/4.5 are known,[3] and a 18cm f/4.5 is reported.[4] On the 21cm f/4.5, the barrel is black and is surrounded by an aperture ring graduated from 4.5 to 45. The focal length 21cm is repeated next to the aperture scale.
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| Simlar 7.5cm f/3.5 lens in a KOO-Tiyoko shutter on a GSK-99. Picture by Dirk HR Spennemann. (Image rights) |
Aerial lenses, for military use
The Simlar 7.5cm f/3.5 was mounted on the GSK-99 aerial camera. The Simlar is normally found on those cameras made by Tōkyō Kōgaku, whereas those made by Konishiroku normally have a Hexar.
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| Simlar 179.5mm f/4.5 no.53 and 180.2mm f/4.5 no.187, for SK-100 aerial camera. Picture by eBayer Hbpartner. (Image rights) |
Simlar 180mm f/4.5 lenses were also made for the larger SK-100 aerial camera. The lenses are engraved with the precise focal length, for example 179.5mm or 180.2mm on the actual examples photographed in this page.
Tele-Simlar 40cm f/5 lenses were used on other aerial cameras, such as the Type 1 vertical mapping camera by Tōkyō Kōgaku, displayed in the Smithsonian National Air and Space Museum.[5]
Wide-aperture lenses
Simlar 50mm f/1.5
The Simlar f/1.5, designed by Tomita Ryōji (富田良治),[6] was the first wide-aperture lens developed by Tōkyō Kōgaku. The design has seven elements in four groups.[6] A patent for that lens was filed in November 1938 and published in June 1940.[6] In the patent, reproduced below, the lens is mentioned as a "photography lens" (写真鏡玉), and a scheme is drawn for a 100mm f/1.5.[6]
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| Patent publication no.S15-3014, for the Simlar f/1.5. Downloaded from the IPDL, in accordance to the IPDL policies. |
The lens was first manufactured as a 50mm f/1.5 for X-ray photography, made from c.1941.[7] It was mounted in a fixed rigid barrel on a special X-ray camera made by an unknown manufacturer, perhaps Tōkyō Kōgaku itself.[8] It is said that at least some lenses were supplied to the 2nd Army Aeronautical Engineering Institute of Tachikawa.[9]
After World War II, the lens was produced in Leica screw mount and sold on the Leotax, see Tōkyō Kōgaku lenses in Leica screw mount.
Simlar 50mm f/0.7
The first Simlar 50mm f/0.7 was developed by Tomita Ryōji around 1941.[10] It has eight elements in four groups.[11] Its exact purpose is unknown, either X-ray photography or night reconnaissance photography. The image circle is 26mm,[10] precluding its use on full-frame 35mm film, and barely sufficient for 18×24mm half-frame exposures (whose diagonal is 30mm).
At least one surviving example of the wartime 50mm f/0.7 is known.[12] It has a large black barrel, 128mm long and 90mm in diameter, and weighs 1kg.[13] There is a fine screw thread at the base of the barrel, 66mm in diameter and 0.5mm in thread.[13] The flange-to-film register is 33.3mm, but the lens rear portion is only 7mm away from the film stock.[13] The aperture ring is graduated from f/0.7 to f/8, and the diaphragm has 18 blades.[13] The surviving example has serial number 5, and is engraved Simlar 1:0.7 f=50mm Tokyo Kogaku Nr.5 around the rim.[14]
Notes
- ↑ Shirazawa, p.15, and this page of the Topcon Club website.
- ↑ 2.0 2.1 Shirasawa, p.63.
- ↑ Examples pictured in Shirasawa, p.63, and in this page of the Topcon Club.
- ↑ Lens reported in this page of the Topcon Club.
- ↑ Example pictured in this page of the NASM.
- ↑ 6.0 6.1 6.2 6.3 Patent publication (特許広告) no.S15-3014, available in the IPDL trademark database
- ↑ Shirasawa, p.50.
- ↑ Camera pictured in Shirasawa, p.51.
- ↑ Shirasawa, p.51, mentions the "Aeronautical Institute of Tachikawa" (立川の航空研究所). The exact name is given in this page of the Japanese Wikipedia.
- ↑ 10.0 10.1 Shirasawa, p.51.
- ↑ Scheme in Shirasawa, p.55.
- ↑ Example pictured in Shirasawa, pp.54–5.
- ↑ 13.0 13.1 13.2 13.3 Specifications in Shirasawa, pp.53–5.
- ↑ Pictures in Shirasawa, pp.54–5, and specifications on p.53.
Bibliography
- Shirasawa Akishige (白澤章茂). Topukon kamera no rekishi. (トプコンカメラの歴史, History of Topcon cameras.) Tokyo: Asahi Sonorama, 2007. ISBN 978-4-257-12051-3.
- Tōkyō Kōgaku. Japanese patent (特許) no.138670. Applied for (出現) on Nov. 5, 1938 and published (公告) on Jun. 15, 1940. Publication extract (特許公告) no.S15-3014 available in the IPDL patent database.
Links
In English:
- Type 1 mapping camera by Tōkyō Kōgaku, with Tele-Simlar 40cm f/5 lens, at the Smithsonian National Air and Space Museum
In Japanese:
