PM I, PM II
Development of the PM series of photographic devices began in the mid 1920s. The PM I and PM II were launched in 1934. The device had been changed from a horizontal to a vertical design.
The PM III and PM IV models were launched before the Second World War. Primarily these models were used to photograph metal specimens and utilized either large-format dry plates or roll film. The devices did not have light meters, so taking an image with the right exposure demanded considerable effort and know-how. The models manufactured after the War could be used with 35mm film.