I've never quite understood where the 1 in 135 came from. Can someone clarify? It's always bugged me.
according to wikepedia:135 film. The film is 35 mm (1.4 in) wide. Each image is 36×24 mm in the most common "full-frame" format (sometimes called "double-frame" for its relationship to the "single frame" 35 mm movie format).