ISO 3641:1976

Overview

ISO 3641:1976 - Cinematography - Motion-picture camera cartridge, 8 mm Type S Model II specifies the external dimensions, cartridge–camera fit, and take-up core drive/core dimensions for the 8 mm Type S film camera cartridge (Model II). The standard defines the physical interface between cartridge and camera so cartridges from different manufacturers will fit and drive reliably. It includes datum plane definitions, dimensional tables and figures, and assembly/clearance requirements for an assembled cartridge containing film.

Key topics and technical requirements

• External dimensions and tolerances: precise diameters, radii and linear measures for the cartridge body and openings are given in figures and tables to ensure interchangeability.
• Datum planes: three mutually perpendicular datum planes (Z primary, Y secondary, X tertiary) are established from seating bosses and core axes to control orientation and mating with camera parts.
• Core openings and coaxiality: take-up and supply core openings and associated core-post/coaxial drive features must meet tight alignment - coaxiality within 0.4 mm (0.016 in).
• Start-of-drive torque: the minimum torque required for the take-up spindle at start of drive is specified as 0.00343 N·m (0.0405 ozf·ft).
• Rotation clearance: a required clearance of 1.0 to 1.7 mm (0.04 to 0.07 in) must exist during rotation, regardless of light-trap construction.
• Sealing and tape limits: if tape is used to seal the cartridge, it must remain within specified dimensional limits so it does not interfere with the fit.
• Design aids and driving teeth: annex provides recommended take-up spindle tooth shapes and additional dimensions to aid common design.

Note: ISO 3641 cites related patent considerations; Fuji Photo Film Co. Ltd. identified patents relevant to cartridge design and has provided licensing assurances.

Applications

• Ensures mechanical interchangeability of 8 mm Type S camera cartridges across camera manufacturers and film suppliers.
• Used in design, manufacture and quality control of cartridges, camera cartridge bays, take-up spindles and alignment fixtures.
• Guides repair shops, restoration projects, and heritage cinematography equipment suppliers working with vintage 8 mm camera systems.

Who should use this standard

• Camera and cartridge designers and mechanical engineers
• Film cartridge manufacturers and OEM suppliers
• Quality assurance and test engineers in cinematography hardware
• Archivists, museum conservators, and technical restorers handling 8 mm equipment

Related standards

• ISO 1700 - 8 mm Type S raw stock film cutting and perforating
• ISO 1787 - Camera usage of 8 mm Type S perforated film
• ISO 2863 - Run length for 8 mm Type S cartridges
• ISO 3025 - Film load position for 8 mm Type S cartridges
• ISO 3646 - Slots and projections for film speed and identification

Keywords: ISO 3641:1976, 8 mm Type S camera cartridge, cartridge–camera fit, take-up core drive, cinematography standards, motion-picture film cartridge dimensions.