Rosco 85

Overview

"Rosco 85" refers to the light filter sheet RoscoSun 85 (Cinegel number #3401) manufactured by Rosco. It is an amber-colored conversion filter from the Cinegel series, which lowers the color temperature of daylight to match artificial light sources at 3200 K (Tungsten/Halogen). The name is derived from the classic photographic conversion filter Wratten 85; the filter is the lighting equivalent, meaning it is placed in front of windows or lights, not in front of the lens.

Unlike CTO (Color Temperature Orange) filters, which are offered in graduated values (1/8, 1/4, 1/2, Full, Double), the 85 is a specific standard window correction tuned for the transition from 5500 K → 3200 K.

Technical Data

The filter is manufactured on a heat-resistant polymer base using the deep-dye process. Available as sheets in the size 20" x 24" (approx. 50 x 61 cm) as well as in rolls of various widths (e.g., 60" x 20' or extra-wide rolls).

On-Set Usage

The most common application is window correction: If an interior is lit with Tungsten artificial light (3200 K), the daylight entering through the windows appears significantly too blue in comparison. A Rosco 85 filter stretched across the window converts the incoming daylight to a color temperature that matches the artificial light, creating a uniform lighting mood and allowing for a white balance set to 3200 K.

Similarly, the filter can be placed in front of daylight fixtures (e.g., HMIs) to match their output to a Tungsten environment. Since the filter transmits approximately 58% of the light, the correction is accompanied by a moderate light loss.

Variations

Rosco also offers the 85 conversion combined with Neutral Density (ND) filters, such as Sun 85N.3 (adding about one stop of light reduction) or stronger ND combinations. These combination filters are used when, in addition to color correction, bright window areas need to be dimmed in intensity.