Aluminum frame for securing color filters in front of lighting fixtures. Standard sizes with spring-loaded clips, heat-resistant to 232°C.
Technical Details
Commercially available gel frames are made of 1-2 mm thick aluminum with rounded corners and a film thickness of 0.1-0.2 mm. The gels are secured in the frame with spring-loaded clips or tape. Heat-resistant gels can withstand temperatures up to 232°C, while standard gels begin to melt at 70°C. Common systems include the Lee Filters series with 204 colors or the Rosco Supergel collection with 386 variants. Magnetic frames for LED panels use neodymium magnets with a field strength of 1.2-1.4 Tesla.
History & Development
Gelatin-based color filters originated in 1884 at London's Drury Lane Theatre. In 1963, Rosco developed the first polyester-based gels, followed by Lee Filters' polycarbonate gels in 1975. The integration of dichroic coatings began in 1982 for tungsten spotlights. With the LED boom starting in 2008, self-adhesive gels for temperature-sensitive applications entered the market. Today, CTO/CTB (Color Temperature Orange/Blue) gels dominate with precise Mired shift values between 81-285.
Practical Use in Film
Roger Deakins used intense orange gels (Lee 204) for the Las Vegas sequences in "Blade Runner 2049" (2017), combined with haze for atmospheric depth. For night shoots, 1/4 CTO gels (Lee 205) correct the 5600K daylight temperature of HMI lights to a warm 4300K. Diffusion gels like Lee 250 reduce hard light by 1.3 stops while simultaneously scattering it. ND (Neutral Density) gels in 0.3-2.1 density stops allow for exposure reduction without color shift.
Comparison & Alternatives
Dichroic filters offer more precise color reproduction but cost 15-20 times more than gels and break if dropped. DMX-controlled LED panels are increasingly replacing gel filters but achieve only 85% of the color saturation of high-quality gels. Spinning filter wheels in moving lights automatically switch between 6-8 colors but are limited to this selection. Color gels remain indispensable for precise color correction and special effects, while LEDs dominate rapid color changes.