COLOR WAVELENGTH (ANGSTROM)

byTed Peterson
In color photography you have color film. Color film is sensitive to all colors but its response to different colors will not be the same. Some film will like one color more then another color.
An light source used with any color film should radiate the proper amount of energy color in each of the colors areas of that film to bring the film back to the correct color. All light travels through space as a vibration of various wave lengths. It is possible to designate the exact areas in which the light radiate the energy.
The wavelength of each color is measured in a unit called Angstrom. One Angstrom unit is equal to one hundred millionth of a centimeter.
Light will go from about 3,000 A units to over 11,000 units. Following are the different colors and their wavelengths. The symbol that is used for this unit is K for color temperature. :
Ultraviolet - Shorter than 3,770 K. units.
Violet - From 3,770 to 4,300 K. units.
Blue - From 4,300 to 4,550 K. units.
Blue Green - From 4,550 to 4,850 K. units.
Green - From 4,850 to 5,400 K units.
Yellow - From 5,400 to 5,900 K. units.
Orange - From 5,900 to 6,300 K. units.
Red - From 6,300 to 7,550 K. units.
Infrared - More than 7,700 K. units.
As you can see different colors travel at a different frequency and the film has to be able to record all the different colors the same. NO film can do this. The film manufactueres will make a film that will be better with one color over another color. In print film, if the color results are off one or the other the lab can correct the picture when they print the picture. You can not do this with slide film. In slide films you need to use the correct film, use a filter to correct the film, or scan the film into a computer and then reproduce the slide after corrected the picture.
Different light source will give off different degrees or wavelength of light. Below is a listing of the different wavelengths.
Electric Heaters - 1,000 K.
Candles From 1,800 to 1,950 K.
Sunrise - 1,900 to 2,000 K.
Incandescent Lamp - 2,650 K. ( Approx).
Photoflood - 3,200 to 3,400 K. (Depending on use.)
Clear Flash - 3,800 K.
Standard Fluorescent Bulbs - Approx. 4,500 K.
Sunlight - Approx. 5,400 K.
Blue Photo Flash - 6,000 K.
Daylight Fluorescent - 6,500 K.
Blue Sky - 11,000 K.
Most print films and black and white films can be used under any of the above light source. Slide film is different. If you buy daylight film and want to take pictures at night under fluorescent or incandescent light it is best to use night slide films. You can use daylight film with a correction filter in front of the lens. If you do not the slide will have a redish cast. If you are using an indoor slide film outside and no filter it will have a little too much blue unless a filter is used. Follow the instructions that comes with the films.
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