Perf, Perforations

Perforations, Perfs or Sprocket Holes are punched into one or both sides of the film stock when it is manufactured. When the film is loaded into a camera, a corresponding pin or claw engages in these perfs to move the film through the camera's film transport mechanism. For each exposure, the film is pulled down into the gate, held still and exposed. The film transport mechanism then pulls the film down to expose the next frame.

35mm and standard 16mm film has sprocket holes on both sides. Super16 mm film has sprocket holes down one side only which allows the other side to be used as increased picture area thus giving the super 16mm 15:9 aspect ratio