Three-Dimensional Photography - Principles of Stereoscopy

124 THREE-DIMENSIONAL PHOTOGRAPHY

use with any film, and when using daylight film this is extended

to 30,000K.

These filters are arranged in graded steps, the temperatures

corresponding to the steps are: 2800, 2900, 3000, 3200, 3400, 3600,

3800, 4300, 4800, 5400, 5900, 6500, 7100, 8000, 9500, 11,000,

13,000 16,000, 20,000, 25,000, 30,000. The blue filters (red ab-

sorbing) are indicated by B, the blue absorbing (pink) filters are

“C.” The depths of color range by numerical values, G, 1/4, 1/2,

Thus to correct daylight film for wire filled flash, you find that

the film is balanced for 5gooK, the flash has a color of 38ooK and

to compensate it is necessary to use a B2 filter.

Let us assume that, like many others, you make a practice of

using only Type A film with the-corrective filter. This is your

scheme of conversion for several different lights:

1, 2, 3, 4, 5, 6, 7 and 8.

Projection bulbs.

White fluorescent

Wire filled flash.

Noon sun .........

Daylight fluorescent ................................ C4
Open bright sky, no direct sun. .C5 to C8 (Max. ii,wK)
(The “B” filters are blue in color, the “C” type is pink.)
But this is not all. When you gain experience in the use of
correction filters you can use them to correct “local” color such
as a reflection from a red brick wall. The color meter will give
you the analysis if you use it to measure the actual light which
falls upon the subject.
You can also make a color reading, and then deliberately over-
or under-correct, to produce an effect which is warmer or cooler
than normal, and for certain experimental and “effect” purposes
you can swing very wide of standard and produce deliberately
falsified effects.
In short, color is a most flexible medium, and once you gain
control of it, you will find that instead of being one of the un-
predictable factors, it is of very great service. For example, one
photographer produced beautiful, blue-haze effects when making