What is the basic gauge most commonly used for both still photography and motion pictures?

Question

The standard negative pulldown for 35 mm motion picture film is four perforations per frame along both edges, which makes for exactly how many frames per foot?

Answer 1

35 mm
A wide variety of largely proprietary gauges were used by different camera and projection systems invented around the late 19th to early 20th centuries, ranging from 13 mm to 75 mm (0.51–2.95 in).