Rengō Kōki (聯合光機, meaning Allied Optical Instruments) was a Japanese camera maker from 1939 to about 1943. It made the Semi Renky and New Semi Renky 4.5×6 cameras, and certainly also the Renky accessory rangefinder, Renky and Renky II enlargers and Renko 75/4.5 enlarging lens distributed by Fuku Bōeki. The original Semi Renky was very similar to the Semi Olympic introduced by Asahi Bussan and manufactured by Riken's subsidiary Asahi Kōgaku Kōgyō. It is not known if the companies were related or if Rengō merely copied the Semi Olympic.
- ↑ 聯合: "Kokusan shashinki no genjōchōsa" ("Inquiry into Japanese cameras"), items 73–4. 光機: Kokusan kamera no rekishi, items 321–2. The name "Rengo Koki" is written on the cameras with no macrons.
- Asahi Camera (アサヒカメラ) editorial staff. Shōwa 10–40nen kōkoku ni miru kokusan kamera no rekishi (昭和10–40年広告にみる国産カメラの歴史, Japanese camera history as seen in advertisements, 1935–1965). Tokyo: Asahi Shinbunsha, 1994. ISBN 4-02-330312-7.
- "Kokusan shashinki no genjōchōsa" (国産写真機ノ現状調査, Inquiry into Japanese cameras), listing Japanese camera production as of April 1943. Reproduced in Supuringu kamera de ikou: Zen 69 kishu no shōkai to tsukaikata (スプリングカメラでいこう: 全69機種の紹介と使い方, Let's try spring cameras: Presentation and use of 69 machines). Tokyo: Shashinkogyo Syuppan-sha, 2004. ISBN 4-87956-072-3. Pp.180–7.