Color film

This article discusses the evolution and technology behind color photographic film, with specific focus on motion

pictures.

For the history of film, in general, see 35 mm film The history of color film is long and complex. Color movies started nearly as early as film itself in 1896 with Thomas Edison's hand-painted Anabelle's Dance made for his Kinetoscope viewers. George Méliès was utilizing a similar hand-painting process for his films, including the early pioneer A Trip to the Moon (1902), which had various parts of the film painted frame-by-frame by twenty-one women in Montreuil^[1]in a production-line method.^[2] Between 1900 and 1935, dozens of color systems were introduced, some successfully.^[3]

Tinting was a procedure that dyed the whole film base, giving the image a uniform monochromatic color. This process was popular during the 1920s with specific colors employed for certain narrative effects (red for scenes with fire or firelight, blue for night, etc.).^[2]

Among the early tinting processes, Pathé Fères invented Pathé color (renamed Pathéchrome in 1929^[1], one of the most accurate and reliable tinting systems that incorporated a series of frame-by-frame stencils, cut by pantograph to correspond to those areas to be tinted in any one of six standard colors^[1] by a coloring machine with rollers to color his company's films. ^[4]Katz, Ephriam (1994) (2nd ed). The Film Encyclopedia HarperCollins Press. ISBN0-06-273089-4</ref> After a stencil had been made for the whole film, it was placed into contact with the print to be colored and run at high speed (60 feet per minute) through the coloring (staining) machine. The process was repeated for each set of stencils corresponding to a different color. By 1910 Pathé had over 400 women employed as stencilers in his Vincennes factory. Pathéchrome continued in production through the 1930s.Cite error: A <ref> tag is missing the closing </ref> (see the help page). In essence, the Technicolor three-color system was incorporated into one film. This rendered the Technicolor system releatively obsolete, even though the Technicolor system produced colors that were more precise than tripack film and the dye-transfer print would maintain its color much longer than tripack negative (which fades over time, especially with improper storage).^[5]

Modern color film is made up of many different layers all working together to create the color image. In color negative films there are three main color layers: the blue record, green record and red record; each made up of two separate layers. Each layer contains silver halide crystals and dye-couplers. A cross-sectional representation of a piece of developed color negative film is at right. Each layer of the film is so thin that the composite of all layers, in addition to the triacetate base and antihaliation backing, is less than .0003" thick.^[6]

The three color records are stacked as shown at right with a UV filter on top to keep the non-visible ultraviolet radiation from exposing the silver halide crystals, which are naturally sensitive to UV light. Next, the fast and slow blue sensitive layers, which, when developed, form the latent image. When the exposed silver halide crystal is developed, it is coupled with a dye grain of its complementary color. This forms a dye "cloud" (like a drop of water on a paper towel) and is limited in its growth by developing ingibiting releasing (DIR) couplers, which also serve to refine the sharpness of the processed image by limiting the size of the dye clouds. The dye clouds formed in the blue layer are actually yellow (the opposite or complimentary color to blue).^[7] There are two layers to each color; a "fast" and a "slow." The fast layer features larger grains that are more sensitive to light than the slow layer, which has finer grain and is less sensitive to light. Silver halide crystals are naturally sensitive to blue light, so the blue layers are on the top of the film and they are followed immediately by a yellow filter, which stops any more blue light from passing through to the green and red layers and biasing those crystals with extra blue exposure. Next are the red sensitive record (which forms cyan dyes when developed), and at the bottom, the green sensitive record, which forms magenta dyes when developed. Each color is separated by a gelatin layer which prevents silver development in one record from causing unwanted dye formation in another. The bottom of the whole stack is an antihaliation layer that prevents bright light from reflecting off the clear base of the film and passing back through the negative to double-expose the crystals and create "halos" of light around bright spots. In color film this backing is rem-jet, which is a black-pigmented nongelatin layer on the back of the film base and is removed in the developing process.^[6]

Eastman Kodak manufacturers film in 54 inch wide rolls. These rolls are then slit into various sizes (65 mm, 35 mm, 16 mm) as needed.

Motion picture film, primarily because of the rem-jet backing, requires a different developer bath than standard color film. The developer necessary is ECN-2 (Eastman Color Negative 2). If motion picture negative is run through a standard C-41 color film developer bath, the rem-jet backing will destroy the intregrity of the developer and, potentially, ruin the film.

There are two main companies manufacturing color film for motion picture use: Eastman Kodak and Fuji Films.

In the late 1980s Kodak introduced the T-Grain emulsion, a technological advancement in the shape and makeup of silver halide grains in their films. T-Grain is a tabular silver halide grain that allows for greater overall surface area, resulting in greater light sensitivity with a relatively small grain and a more uniform shape which results in a less overall graininess to the film. This made for sharper and more sensitive films. The T-Grain technology was first employed in Kodak's EXR line of motion picture color negative stocks.^[8] This was further refined in 1996 with the Vision line of emulsions, followed by Vision2 in the early 2000s.

The prefex "52" designates 35 mm negative size, "72" designates 16 mm. The "T" designates a tungsten (3200K) balanced negative and "D" designates a daylight (5600K) negative. The number preceeding this is the film's speed (ISO).

• Vision
  • 5274/7274 Vision 200T
  • 5279/7279 Vision 500T

• Vision2
  • 5201/7201 Vision2 50D
  • 5205/7205 Vision2 250D
  • 5212/7212 Vision2 100T
  • 5217/7217 Vision2 200T
  • 5218/7218 Vision2 500T
  • 5229/7229 Vision2 "Expression" 500T
  • 7299 Vision2 "HD Color Scan film"

Fuji films also integrate tabular grains in their SUFG (Super Unified Fine Grain) films. In their case the SUFG grain is not only tabular, it is hexagonal and consistent in shape throughout the emulsion layers. Like the T-grain, it has a larger surface area in a smaller grain (about 1/3 the size of traditional grain for the same light sensitivity. In 2005 Fuji unveiled their Eterna 500T stock, the first in a new line of advanced emulsions, keeping competitive with Kodak's innovations.

The "85" prefix designates 35 mm stock, the "86" prefix designates 16 mm stock. All stock numbers ending in a "2" are Fuji's Super-F emulsions (1990s) and the stocks ending in "3" are the new Eterna emulsions (currenly only one available, but three more have been announced (January 12, 2006^[9]). Fuji also introduced their Reala film - a color stock with a 4th color emulsion layer, which is also the fastest daylight balanced color motion picture stock ever offered at 500 ISO.

• Eterna
  • Eterna500 8573/8673

• Super-F
  • F-64D 8522/8622
  • F-125T 8532/8632
  • F-250T 8552/8652
  • F-250D 8562/8662
  • F-500T 8572/8672
  • F-400T 8582/8682

• Reala
  • RealA 500D 8592/8692