Correlated Color Temperature

Correlated Color Temperature (CCT) is a visual term often applied to fluorescent and industrial-discharge lamps by the bulb manufacturer. For photographic and video purposes, it should not be used as a reference, unless there is an accompanying Color Rendering Index (CRI) that exceeds 90.

Filters for Other Fluorescents and Industrial Discharge Lamps (Metal-Halide, mercury, sodium)

The term "discharge lamp" includes such diverse sources as fluorescent, HMI, Metal-Halide, mercury, and sodium. For film and video applications, the spectral output of these sources differs widely. But virtually all sources in this class can be corrected with Cinegel or CalColor Filters. The exceptions are Low-Pressure Sodium, which is a monochromatic source, and Clear Mercury, which will only yield marginal photographic results.

The color balance of industrial-discharge sources is usually measured with a three-color temperature meter. By employing the amber, straw or blue filters, the color temperature is lowered or raised as needed. The green region of the spectrum is then adjusted with the green or magenta filters. This technique is described in detail here.

We caution you against using the Correlated Color Temperature data supplied by the bulb manufacturer for determining photographic filtration.

Special Filters for Carbon Arc and HMI

A traditional range of filters is also available for Carbon Arc and HMI correction. These filters are all designed to reduce the color temperature in discreet steps.

CalColor used as Color Compensating CC Filters

The CalColor range of filters is primarily designed as a series of calibrated color-effects filters for film and video.

However, due to the special nature of their design, they can also be used as color compensating CC filters. They therefore provide another means for light source color correction.

The filter recommendations listed below should only serve as broad guidelines. Because of the many variables inherent in lighting and the photographic process, and the differences within bulb class and emulsion types, we strongly suggest photographic testing beforehand.

Diffusion Materials

Lighting fixtures for film and video production usually function by means of a reflector that gathers the light from a point source and focuses it through a lens. The result is a beam that has a high level of intensity or "punch". But these fixtures also present a number of drawbacks: the projected beam field may be uneven in intensity, the beam edge may be too harsh, or the hard shadows created by the beam may be objectionable or unflattering to the subject.

Placed in the beam path, diffusion materials modify the harsh quality of the beam by spreading or dispersing the light. This effectively softens the beam and alters its shadow-casting properties. In addition, diffusion reduces the contrast between highlight and shadow areas.

"Tough" Diffusion Types

The following diffusion groups are designated as "Tough". This term indicates that the base material is a heat-stable polyester that can be used on most high-temperature lighting fixtures.

These materials can be sewn and grommetted to fit butterfly and overhead frames, so they are ideal for tenting or large area diffusion.

"Soft" Diffusion Types

Transmission Loss

Transmission data for diffusion material can often be confusing and misleading, depending upon how the measurements are performed The chart below shows transmission loss when the light source is placed 6 feet from the subject, and the material is placed either at the source, or on a frame 2 feet out in front. All measurements are at the beam center. Placing the diffusion material out in front of the source generally yields higher transmission, as well as increased diffusion effect (a lowering of contrast and softer shadows). Consult Technotes #3 for more details.

Butterflies and Overheads

A number of Cinegel materials are available to fit the standard butterfly and overhead grip frames. (6X6, 8X8, 12X12, 20X20). All materials are supplied from stock, edge-finished with binding and grommets on 24" centers. Custom sizes are also available. #3030, 3032, 3034, 3060, and 3062 have sewn seams. #3014 and 3029 have ultrasonic, butt-welded seams.

Neutral Density Filters

Neutral Density filters are designed to reduce the intensity of light without affecting color temperature. They are usually applied to windows to reduce the level of exterior light and bring it within the range of interior light level.

Neutral Density combined with RoscoSun 85 Correction

Two filters are designed to combine the effect of RoscoSun 85 (daylight-to-tungsten correction) with Neutral Density light reduction.

Rigid Acrylic RoscoLex Panels

Daylight control is also available in 4 ft. x 8 ft. (1.2m x 2.45m) rigid acrylic sheets for light-intensity reduction in 1, 2, or 3 stops. They offer quick set-up, easy handling and multiple re-use.

Roscoflex

Roscoflex materials offer a wide variety of choices for surfacing reflector boards or for use whenever reflected light is required. The product designation generally indicates the quality of the reflection. All materials are fabricated in durable aluminum-faced polyester film.

Bounce Materials

Roscopaks

Color Effects Filters

Rosco offers over 200 colors in three ranges of filters to create various color lighting effects. These are offered under the brand names Roscolux, Supergel and Cinelux.

Roscolux and Supergel

The most widely-used color filters in the world, they are available as Roscolux in North America and as Supergel elsewhere in the world. A unique manufacturing technology insures the longest possible life when used on hot theatrical lights. Three discrete layers are combined in a tri-extrusion process whereby the colored layer is sealed between two microscopically thin layers of clear film. Dye migration is minimized and the effective life of the filter is extended. Sheets 20 in. x 24 in. (50 cm x 61 cm) or rolls 24 in. x 25 ft. (61 cm x 7.62 m).

Cinelux

Cinelux is a selection of color filters from the Roscolux range which are produced in rolls 48 in. x 25 ft. (122 cm x 7.62 m). Cinelux is especially suited for motion picture and television production where larger lighting fixtures are often used, or where color is often mounted on frames out in front of lighting fixtures. These colors have been developed by Rosco over the past 87 years, and the dyes are among the most heat stable available.

CalColor (Calibrated Color by Rosco)

Calibrated Color by Rosco is a series of color effects lighting filters designed specifically to the spectral sensitivity of color film. Series I colors include the primaries Blue, Green and Red, along with the secondaries Yellow, Magenta and Cyan. Series II intermediary colors will follow. Each color is designed in four densities; 15cc, 30cc, 60cc and 90cc, corresponding to the familiar lens filter or color printing calibrations.

In color photography, three light-sensitive emulsion layers separately record the individual blue, green and red components of the spectrum. CalColor filters adjust the transmission of these color components at the individual light source in a familiar and reliable manner. As a result, the cinematographer can exercise selective and predicable control over the coloration of various elements within the scene.

For instance, a CalColor 90 Green selectively enhances green transmission--it does this by effectively reducing both the blue and red transmission by .90 or three stops. Similarly, a CalColor 90 Magenta enhances blue and red transmission by effectively reducing the green transmission by .90 or three stops.

In addition to their use as color effects filters, CalColors serve a number of technical purposes. The primaries in the 90 density offer both the saturation and separation characteristics needed for lighting a clean matte composite background (the complimentary tints then become useful choices for backlighting the subject to neutralize any spill that could cause contamination or color fringing in the matte). They are also useful for color correcting industrial lamps, or in black-and-white photography for altering the tonal rendering of colors in a scene.

For further information, please consult the CalColor swatchbook.

CalColor Kit

Rosco E-Colour

European-style Color Correction and Effects Filters

Rosco has consistently been the recognized leader in filter technology for the past 85 years. Rosco E-Colour continues that tradition with a comprehensive collection of filters for those who are accustomed to the European-style color names and numbering system.

Each E-Colour filter is manufactured through a unique coating process, utilizing the latest in dye and polymer technology. As a result, they equal or exceed the performance of competitive European filter brands. E-Colour filters are available in rolls 48 in. x 25 ft.(122 cm x 7.62 m), or sheets 21". x 24" (53 cm x 61 cm).

Other Cinegel Products

Polarizing Filter
Neutral-grey linear polarizing filter for use on lights. Reduces reflected glare from surfaces such as glass, water, paper, plastics and metal. Best used in conjunction with a lens polarizing filter. Available in sheets 19 in. x 20 in. (48 cm x 50 cm), or rolls 19 in. x 5 ft. (48 cm x 150 cm).

UV Filter
A slightly warm filter that absorbs 90% of UV below 390 nanometers. Available in sheets 20 in. x 24 in. (50 cm x 61 cm), rolls 24 in. x 50 ft. (61 cm x 15.2 m), rolls 48 in. x 25 ft. (122 cm x 7.62 m) or as 48 inch (122 cm) sleeves designed to fit T-8 or T-12 fluorescent lamps.

Heat Shield
A protective colorless filter of extremely heat-stable polymer, specially designed to deflect heat. Available in sheets 20 in. x 24 in. (50 cm x 61 cm), rolls 24 in. x 50 ft. (61 cm x 15.2 m), or rolls 48 in. x 25 ft. (122 cm x 7.6 m).

Thermashield
A transparent film with a multi-layer coating for reflecting most of the damaging infrared heat emitted by film and television lighting fixtures. Available in sheets 12 in. x 12 in (30 cm x 30 cm) or 20 in. x 24 in. (50 cm x 61 cm).