Half scrim with one open side — attenuates light only partially, creating a soft gradual transition between the dimmed and undimmed areas of the beam.
Technical Details
Open end scrims are manufactured in standard sizes of 6", 8", 10", and 12" diameter, corresponding to common lamp sizes. The cylinder length is typically 15-25cm. The mesh fabric can withstand temperatures up to 180°C and weighs between 40-120g depending on the size. Available are Single Scrim (-0.3 stops), Double Scrim (-0.6 stops), and Triple Scrim (-1.2 stops). Attachment is via spring clips or magnetic mounts directly to the lamp housing. High-quality variants feature reinforced edges made of wire mesh.
History & Development
The first open end scrims were developed in 1955 by Matthews Studio Equipment for Hollywood productions. The inspiration came from rigid scrim frames used in theater, which were impractical for mobile film production. In 1962, Mole-Richardson introduced magnetic attachment, significantly simplifying handling. In the 1980s, more heat-resistant materials came onto the market, enabling their use with 10K lamps. Modern LED panels have reduced the demand, but scrims remain standard for tungsten and HMI lights.
Practical Use in Film
Open end scrims are used for gradual light reduction without changing color temperature, for example, in daylight shots with excessively bright sunlight. In "Blade Runner 2049" (2017), DoP Roger Deakins used double scrims on 18K lamps for diffuse interior lighting. The workflow involves direct mounting on the lamp before switching it on, as attaching it later to hot lights can damage the material. Advantages include even light distribution and minimal space requirements. Disadvantages are limited control over light direction and the risk of heat damage if used improperly.
Comparison & Alternatives
Open end scrims differ from silk diffusers by their cylindrical shape and direct lamp mounting. Unlike ND filters, they also alter light quality through diffusion. Modern alternatives include dimmable LED panels and electronic shutter systems. Single scrims are suitable for minor adjustments, double scrims for moderate corrections, and softboxes for strong diffusion with directional control. For HMI lamps over 6K, external diffusion frames are increasingly preferred as they create larger light surfaces.