Kodak ISBN 0-87985-749-8 manual Color Compensating Filters

Below is a conversion table of filter factors to exposure increase in stops.

Filter	+	Filter	+	Filter	+
Factor	Stops	Factor	Stops	Factor	Stops
1.25	1⁄2	4	2	12	32⁄3
1.5	2⁄3	5	21⁄3	40	51⁄3
2	1	6	22⁄3	100	62⁄3
2.5	11⁄2	8	3	1000	10
3	12⁄3	10	31⁄3	–	–

Each time a filter factor is doubled, the exposure needs to be increased by 1 stop. As an example, a filter factor of 2 requires a 1-stop exposure increase. A filter factor of 4 requires a 2-stop exposure increase. Use this example for filter factors not listed in the above table.

Color Compensating Filters

Color compensating filters control light by attenuating principally the red, green, or blue part of the spectrum. While controlling one color, the filter transmits one or both of the other two colors. Thus, color compensating filters can make changes to the color balance of pictures recorded on color films, or compensate for deficiencies in the spectral quality of a light source. For optimum results, use the single recommended color compensating filter rather than combining filters (for example, CC20Y + CC20M = 20R, so using 20R only is preferable). KODAK WRATTEN Gelatin Filters/Color Compensating Filters have excellent optical quality and are suitable for image forming optical systems — over-the-camera lens, for example. For less critical work, you may use KODAK Color Printing Filters (acetate).

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