ISO 25:1994

Overview

ISO 25:1994 - "Cinematography - Camera usage of 16 mm motion‑picture film - Specifications" is an international standard that defines essential camera‑side conventions for 16 mm motion‑picture film. It specifies the position and orientation of the emulsion, and the recommended frame rates of exposure for both silent and sound 16 mm film perforated along one or both edges. This second edition (1994) replaces the earlier edition and is aimed at ensuring compatibility between cameras, projection, and post‑production processes.

Key topics and technical requirements

• Scope: Applies to 16 mm silent and sound motion‑picture film perforated along one or both edges.
• Emulsion position and orientation: The standard prescribes how the emulsion area should be oriented in the camera (figure shows the film as seen from inside the camera, looking toward the lens, with the photographic layer away from the observer). Conformance ensures consistent image orientation and alignment.
• Frame rate (exposure speed):
  • 24 frames per second (fps) is specified for film containing a sound record or used with a sound record (both photographic and magnetic sound).
  • 18 fps may still be encountered for some silent films (historical practice).
  • For non‑sound films, 24 fps is normally recommended but may vary depending on intended use.
  • Special “no sound” films (time‑lapse, high‑speed) may be shot at any frame rate; the intended projection rate should be noted.
  • Television‑targeted films may be shot at 25 fps (50 Hz systems) or 30 fps (60 Hz systems); 24 fps may also be used.
• Normative references: Cites related ISO standards that affect film cutting, perforating and projector usage.

Applications and who uses ISO 25:1994

• Cinematographers and camera operators using 16 mm film who need standardized guidance on film loading orientation and exposure speeds.
• Camera and equipment manufacturers designing 16 mm camera mechanisms and gate orientation.
• Film laboratories, post‑production facilities and archivists ensuring proper handling, projection and digitization of 16 mm material.
• Film restoration specialists and educators working with historical and contemporary 16 mm workflows.
• Standards committees and technical documentation authors referencing consistent camera usage practices.

Related standards

• ISO 26:1993 - Projector usage of 16 mm motion‑picture film (projector specifications)
• ISO 69:1990 - 16 mm film cutting and perforating
• ISO 466:1976 - Image produced by 16 mm camera aperture (position and dimensions)

Keywords: ISO 25:1994, 16 mm film, cinematography standard, emulsion orientation, frame rate, sound film, silent film, camera usage, film perforation.