Film perforations

Film perforations (also known as perfs and sprocket holes) are the holes placed in the film stock during manufacturing at regular intervals. Perforations are used for transporting (by sprockets and ) and steadying (by pin registration) the film when moving through a motion picture camera or film projector. Films may have different types of perforations depending on film gauge, film format, and intended usage. Perforations are also used as a standard measuring reference within certain camera and projection systems to refer to the size of the image in the frame. For instance, 35mm Academy is also known as 4 perf-35mm; VistaVision is 8 perf-35mm; Todd-AO70mm film is 5 perf-70mm; and IMAX is 15 perf-70mm. Non-standard perforations also exist, especially on older and very early film formats, such as those produced by the Lumière brothers, or 9.5mm formats produced by Pathe-Freres.