A challenging subject for any color film, this car is plastered with toys.
Color films are categorized into sensitivity classes according to the type of light falling on the scene to be photographed. It’s impossible to make one film that will accurately record color under all light sources, so color films are manufactured for different standard light sources. Daylight film, for instance, is for use in normal daylight. Type A film is for use with flood lamps that have a color temperature of 3400K (degrees Kelvin), and Type B film is for 3200K lighting. (See Light and its color in our section on Light for a discussion of color temperature, which is different from normal hot/cold temperature that we feel.) Each type of film can be used under the other lighting conditions and still render colors correctly when filters are employed. Since corrective filters affect the overall light that reaches the film, mixed lighting (e.g. daylight and flood lamps together) will not properly record the color from both types of light in the same film frame.
Daylight film, the most commonly-used color film, also properly records color sensitivity in scenes illuminated by electronic flash or blue flash bulbs, although the actual light from electronic flash needs corrective filtration for truly-accurate color rendition. The corrective filters are generally built in to the flash unit.
COLOR INFRARED FILM
Although most people tend to think of infrared film as a black and white film, color infrared film captures light that black and white infrared films cannot. More correctly termed “false color” film, it is more sensitive to longer wavelengths. Rather than recording red, it records infrared. Blue or violet (the shorter wavelengths) are not recorded at all.
ULTRAVIOLET (UV) RADIATION
All film is sensitive to ultraviolet radiation. There is no special ultraviolet film emulsion - that is, no film is sensitive only to UV radiation.
The amount of ultraviolet radiation in ordinary daylight is negligible and has little effect in general-purpose photography. But when you are shooting aerial pictures at high altitudes, the effect of ultraviolet can be a pain in the neck because it so strong. UV is rendered as a shade of blue in color film. To further complicate matters, UV photographs in a different plane than that of visible light, superimposing an unsharp UV image over a picture taken in normal light. Sometimes, the effect is so minimal that it has no effect on your image, but at other times you may wonder why your image appears so out-of-focus or unsharp. UV is the problem. The answer is to use a filter that absorbs ultraviolet light (a UV filter), preventing it from affecting the film. Many lenses are coated to block UV radiation. Note that digital cameras, as a rule, are less sensitive than film to UV light, and rarely benefit from the use of UV filters.
This image could have been taken on color daylight film or Type A or B film using filters. (It was actually taken without film, on a digital camera.)
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