American manufacturer of lighting filters, color gels, and diffusion materials — known for the GAM color system and frost products.
Technical Details
GAM filters are manufactured in nine standard sizes: 100mm, 132mm, 165mm, 190mm, 229mm, 267mm, 305mm, as well as the rectangular formats 254x305mm and 610x610mm. The color filters are based on the subtractive color system and reduce light output between 10% (Light Frost) and 95% (Deep Blue), depending on the density. Diffusion gels like "Tough Frost" scatter light by 30-60 degrees, while textured gobos create projection patterns with a depth of field from 0.5m to infinity. The material thickness is standard 0.18mm for filters and up to 0.3mm for metal gobos.
History & Development
In 1973, Rosco introduced the first standardized color filters; GAM followed in 1976 with its own systems. The breakthrough came in 1982 with the introduction of heat-resistant polycarbonate gels that could withstand 2500W HMI lights without melting. In 1995, digitalization revolutionized gobo design – computer-generated patterns replaced hand-drawn templates. Since 2010, LED-compatible filters have dominated the market, remaining color-accurate even with 3200K LEDs.
Practical Use in Film
In "Blade Runner 2049," Roger Deakins used GAM gobos with Venetian blind patterns for the iconic louvre shadows in Deckard's apartment. For daylight shots, CTO (Color Temperature Orange) filters are often used to match 5600K HMIs to 3200K tungsten. Diffusion gels like "Light Grid Cloth" reduce harsh shadows by 40% in portrait shots, while "Heavy Frost" serves as an affordable softbox alternative. Filter changes take 15-30 seconds, which is why gaffers often have multiple lights with different filters ready for complex setups.
Comparison & Alternatives
GAM directly competes with Rosco Supergel and Lee Filters, with GAM traditionally delivering stronger reds. Modern LED panels with RGB mixing are increasingly replacing color filters but only achieve 85% of the color saturation of gel filters. Digital gobos in moving lights offer more flexibility but cost 20 times more than a static solution. For budget productions, GAM filters remain unrivaled: a complete set costs €200 compared to €15,000 for comparable LED technology.