Color gel

Color gel
Many color gels organized, some in gel frames

A color gel or color filter (UK spelling: colour gel or colour filter), also known as lighting gel or simply gel, is a transparent colored material that is used in theatre, event production, photography, videography and cinematography to color light and for color correction.[1] Modern gels are thin sheets of polycarbonate or polyester, placed in front of a lighting fixture in the path of the beam.[2]

Gels have a limited life, especially in saturated colors. The color will fade or even melt, depending upon the energy absorption of the color, and the sheet will have to be replaced. In permanent installations and some theatrical uses, colored glass filters or dichroic filters are being used. The main drawbacks are additional expense and a more limited selection.

Contents

History

In Shakesperean theatre, red wine was used in a glass container as a light filter. In later days, colored water or silk was used to filter light in the theater. Later, a gelatin base became the material of choice. Gelatin gel was available at least until 1975. The name gel has continued to be used to the present day. More heat-tolerant self-extinguishing acetate-based materials (marketed as Cinemoid and Roscolene) were developed to deal with higher output light sources. This material fell out of favor, since it could not withstand the higher temperatures produced by the tungsten halogen lamps that came into widespread use in the late 1960s. The acetate-based material was replaced by polyester and polycarbonate based gels. Those materials have superior heat tolerance when compared to acetate-based gels. Polyester "gels" were introduced in 1969 as Gelatran, the original deep dyed polyester. The Gelatran process is still used today to create GAMColor. Other color manufacturers, such as Lee Filters and Apollo Design Technology use polyester as their color substrate. Lee and Apollo use the surface dyed process. Roscolux is 70% polycarbonate and 30% deep dyed polyester. Almost every color manufacturer today uses either polycarbonate or polyester to manufacture their "gels". Even today's gels can burn out (to lighten in color starting in the center) easily, rendering them useless. To help combat this, a high temperature (HT) material (polyester having the highest melting point 480 °F (250 °C)), can be used to help prolong the life in high-heat output lighting instruments. As instrument design improves, it has become a selling point on many lights to have as little heat radiating from the front of the fixture as possible to help prevent burn-through, and help keep the stage and actors cooler during performances.

A motorized color gel

In the theater, gels are typically available in single 20×24-inch (500×600 mm) sheets, which are then cut down to the appropriate size before use. The size originates from the gelatin days: it is the same as a standard baker's sheet, which was used to cast the sheets. In the film industry, gels are usually cut straight from rolls 24" or 48" (600 mm or 1200 mm) wide and 50' (16 m) long, as the size required may vary from a couple of inches to gel a Dedolight or a practical halogen spotlight in a ceiling to many feet to gel a whole window, so a standard sized sheet would be impractical.

Colors

Similar colors may vary between different companies' formulations - for example, many have a color named "bastard amber", but the transmitted color spectrum may be different. For this reason, gel colors are not referred to by name. Using nature’s color spectrum as a guide, Apollo Design Technology uses a four digit number to designate and locate specific color transmissions: Visible Spectrum.[3] Some manufacturers use a code consisting of a letter and number combination. For example, G841 is a dark blue made by Great American Market (GAM), and R02 is a light amber made by Rosco and L216 is a diffusion filter made by Lee Filters.

Manufacturers produce swatch books, which contain a small piece of each color available, adjacent to its color code, to simplify ordering. Swatch books enable designers and technicians to have a true representation of the manufacturers' range of color.

Most designers choose a limited color palette for generic applications because it is financially and logistically difficult to have access to all colors for a single show.

Color correction gels absorb light of some wavelengths more than others. This Rosco gel has a low transmittance at long wavelengths.

There are also gels for color correction, such as CTB and CTO, "Color Temperature Blue", and "Color Temperature Orange" respectively. Color correction gels alter or "correct" the color temperature of a light to more closely match the color temperature of a film negative or the white balance of a digital imager. Specifically CTB, which is blue in appearance, will correct tungsten lights that typically have a color temperature in the range of 3,200 kelvins to 5,700 kelvins to more closely match the color temperature of "Daylight" negative, which is usually around 5,400 kelvins (nominal daylight[4]). CTO, which is orange in appearance, will correct a "Daylight" balanced light source (such as many common HMI bulbs) to match the color temperature of Tungsten negative, which is typically 3,200 kelvins. There are "half" and "quarter" variations of the common color correction gels. It is common to use color correction gels for artistic purposes and not just for negative-to-lightsource correction.

Most ranges of gels also include non-colored media, such as a variety of diffusion and directional "silk" materials to produce special lighting effects. "Opal" for example is an opalescent or translucent diffusion filter.

It is common for a gel manufacturer to publish the transmission coefficient or even the spectral transmittance curve in the swatch book and catalogs. A low transmittance gel will produce relatively little light on stage, but will cast a much more vivid color than a high transmission gel, because the colorfulness of a light source is directly related to narrowness of its spectral linewidth. Conversely, the flatter its curve becomes, the closer the gel is to a neutral density filter.

See also

References

  1. ^ http://www.destudiodublin.com/About/Glossary-deStudio.htm#G
  2. ^ "Color Gels". Academic dictionaries and encyclopedias. http://en.academic.ru/dic.nsf/enwiki/167702. Retrieved 16 August 2010. 
  3. ^ http://en.wikipedia.org/wiki/Visible_spectrum Visible Spectrum
  4. ^ Values from the course-notes of cinematographer Tom Mangravite

External links


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Gel (disambiguation) — Gel may refer to: * Gel, a jelly like substance * Personal lubricant used for sex purpose * Gel, a fictional character from The Tribe , played by Vicky Rodewyk * Gel battery is a rechargeable valve regulated lead acid battery with a gelified… …   Wikipedia

  • Color scroller — A color scroller or color changer is an electro mechanical lighting accessory used in theater, film, dance and concerts to change the color projected by stage lighting instruments without the need of a person to be in the vicinity of the light. A …   Wikipedia

  • Gel bracelet — Gel bracelets or jelly bracelets are an inexpensive type of wristband similar to a large diameter O ring. They come in a variety of colors, and dozens can be worn on each arm. They have been popular in waves throughout the Western world and… …   Wikipedia

  • gel de sílice — un tipo de sílice que se presenta en cristales de color azul con gran poder deshidrante. Cuando ha absorbido, cambia de color al rosa, pudiéndose regenerar calentándola a 105ºC Diccionario ilustrado de Términos Médicos.. Alvaro Galiano. 2010. gel …   Diccionario médico

  • Color correction — This article is about color correction using lighting and camera filters. For video color correction in post production, see Color grading. For color correction of still images in post production, see Color balance. For mutual color correction of …   Wikipedia

  • Color temperature — The CIE 1931 x,y chromaticity space, also showing the chromaticities of black body light sources of various temperatures (Planckian locus), and lines of constant correlated color temperature. Color temperature is a characteristic of visible light …   Wikipedia

  • Color marker — A Color marker is used to monitor the progress of agarose gel electrophoresis and polyacrylamide gel electrophoresis (PAGE) since DNA, RNA, and most proteins are colourless. They are also referred to as tracking dyes. Commonly used color markers… …   Wikipedia

  • Gel de sílice — Este artículo o sección necesita referencias que aparezcan en una publicación acreditada, como revistas especializadas, monografías, prensa diaria o páginas de Internet fidedignas. Puedes añadirlas así o avisar …   Wikipedia Español

  • Color of chemicals — The color of chemicals is a physical property of chemicals that in most cases comes from the excitation of electrons due to an absorption of energy performed by the chemical. What is seen by the eye is not the color absorbed, but the… …   Wikipedia

  • Color magazine — This article is about a type of theater technology. For other uses, see magazine (disambiguation). An example of a color magazine or boomerang A color magazine is a fixture attached to a follow spot that places different color filters in the path …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”