Tōsei Kōki Y.K. (東成光機有限会社, meaning Tosei Optical Instruments) was a Japanese camera maker in the first half of the 1950s. It was based in Koiwamachi, Tokyo.[1] The name Tōsei is reportedly an allusion to the Tokyo-Narita railway line which was running not far from the factory.[2] (Tōsei 東成 is a concatenation of the characters 東 for Tōkyō 東京 and 成 for Narita 成田.)

The company made the Frank Six and Semi Frank folders and the Copenflex TLR, and certainly also the TKS shutters. The Frank Six was first released in mid-1950 by Taiyōdō Kōki as the Beauty Six, but it is not known if the production was transferred to Tōsei Kōki or if the company produced the camera from the start as a subcontractor of Taiyōdō.

The T.K logo of the company depicts a vertical convex lens crossed by a horizontal concave lens. It is very similar to the first Mamiya logo.

Camera list[]

One source attributes the Comex 35 to Tōsei Kōki,[3] but this is perhaps a mistake, due to the fact that the Sanon Six and Comex 35 were sold by the same distributor Takasago.


  1. The exact address was Tōkyō-to Edogawa-ku Koiwamachi 7–321 (東京都江戸川区小岩町7–321). Source: advertisements dated December 1952, January and April 1954, reproduced in Kokusan kamera no rekishi, pp.137–8 and 174.
  2. This page by Terasaki Haruhisa.
  3. See this page at Japan Family Camera.



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