Three-Dimensional Photography - Principles of Stereoscopy

122 THREE-DIMENSIONAL PHOTOGRAPHY

sufficient photographic intensity), and obtain a color picture of
better than average color balance. It is as easy as that.
You can do this simply by placing a filter over each camera
lens, but to select the correct filter you must know the color
composition of the existing light and how far it is out of normal
balance. In short you just know the color temperature of the
existing light and the color temperature for which the film is
balanced. By filter compensation you can then easily coordinate
film and light balance.
Practically, this is easy and pays excellent dividends in increased
color quality. There is just one thing against it. It is just too much
trouble to carry around the necessary filters and to make a CT
reading of the light. Too-much-trouble! The same old thing
which is responsible for such a tremendous amount of photo-
graphic inferiority among the work of our amateurs.
So much for “Why,” now for the “What” and “How.”
Consider these color temperatures:
Dull red-hot iron ............................... 8mK
Candle ......................................... 1850K
Ordinary electric lamp, special .................. zgooK
Projection lamp, special ........................ .3zmK
TUNGSTEN COLOR FILM .......................... .3zmK
SF/SM flashbulbs .............................. .33mK
Photoflood lamp 34mK
TYPE A FILM 34mK

Blue photoflood 5-K

Noon sunlight 54mK

Sun in blue sky 59mK

Eectronic flash about 7-K

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Wire filled flashbulb ........................... .@OK

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Blue sky .............................. goo0 to 30,000K

Suppose you have Type A film in your camera, and you wish to

make a sunlight exposure. What should you do? The film is bal-

anced for light of 34ooK, the light you will use has a CT of

54ooK, a difference of 2000K. The sunlight is higher in tempera-

ture than the film balance which means it is more blue. You must

use a filter which will absorb a sufficient amount of the blue of

sunlight to reduce its effective CT to 34ooK. This is exactly what

the familiar conversion filter does.

If you use daylight film, balanced for 5gooK and you are using

photoflood light at 34ooK, you have a film balanced for blue and