17.5mm Film

17.5mm film was a short-lived theatrical exhibition format created during WWII to more economically utilize existing 35mm film stock. Basically, it is 35mm film split in two lengthwise, resulting in two reels of film each with a width of 17.5mm and perforations along only one side.

The format continued to be used after WWII especially in developing nations or for projects in which 35mm film would have been too costly. 17.5mm film was created for both optical and magnetic audio recording.

Since 17.5mm film is made from 35mm film, it has the same sprocket hole size and number of sprocket holes per foot as 35mm film (below).

16mm film sprocket holes are smaller and more widely spaced than those found on 17.5mm film.