In Japan, the Semi format (セミ判) is the 4.5×6cm format, giving 16 exposures on 120 film. The word "Semi" (セミ) often appears in the names of older Japanese 4.5×6 cameras. Most of these are folders: see the page about the Japanese 4.5×6 folders. There is also a handful of models with a rigid body and a telescopic lens, made in the late 1930s and early 1940s. There are over 80 camera names using the the word "Semi" listed in the adjacent chart.
The word Semi was abandoned for camera names in the 1950s, together with the disappearance of the 4.5×6 models. The format was revived in 1975 with the Mamiya M645, and the term "645" has since been used in many camera names, like the Fujica GS645, Pentax 645, Contax 645 AF and Bronica RF645.
|Semi Lucky, Fujimoto 1938|
image by Geoff Harrisson (Image rights)