■ U.S. DEPARTMENT OF COMMERCE National Bureau of Standards Washington, D.C. 20234 NBS Misc. Publ. 259* Issued June 26, 1964 Price 5 cents SELECTION OF CAMERA FILTERS FOR COLOR PHOTOGRAPHY One of the problems facing the serious color photographer — whether he is a hobbyist or a scientist trying to record accurately some physical phenomenon — is matching his color film to the light he is using to take the picture. Color films are usually balanced for a particular kind of light, classified as "daylight," "flash," "3200 °K," or "photoflood." When a film is used in light with a different color balance, filters are used over the camera lens to bring the combination back into agreement. This chart provides a quick and easy way to select the right filter for almost any combination of light source and color film. A straightedge laid across the three scales so that it connects the light source and the color film will cross the center line at a point corresponding to the proper filter. Notations consisting of a series of filter designations (e.g., 80b + 82c + 82a) mean that all these filters should be used at once for proper correction. When color correcting filters are used, the exposure must be increased by the "filter factor" assigned by the filter manufacturer. The chart was prepared by C. S. McCamy of the NBS Photographic Research Section. ANOTHER NBS PUBLICATION OF INTEREST TO PHOTOGRAPHERS Method for Determining the Resolving Pouer of Lenses (NBS Circular 533) provides the photographer with two sets of charts by which the resolving power of a photo- graphic lens may be numerically measured. The accompanying booklet gives a detailed description of the procedure and technique to be followed in order that comparable values may be obtained by different observers. Additional uses of these charts are also described, including the testing of goggle lenses for definition and prismatic power, and the testing of telescopes and binoculars for definition. NBS Circular 533,* Method for Determining the Resolving Power of Photo- graphic Lenses, by Washer and Gardner, $1.75 (add one-fourth for foreign mailing). *For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C, 20402 5 cents *m nmsnvANu mn JMmsirr LIBRAE COLOR FILTER NOMOGRAPH