Movie Makers (Jan-Dec 1947)

61 CONTROLLING COLOR Last of two discussions of color temperature LLOYD W. DURANT ONCE you are acquainted with the basic principles of color temperature and color balance, your next step is to apply this knowledge to actual practice. Remember that color films are balanced according to the color temperatures of certain light sources. The fihner must be constantly on the alert to eliminate any variation between this color balance of the film and the light source employed. The color temperature meter is designed to permit this control by means of visually determining the illumination quality of the light source used. The meter enables one to measure directly the color temperature of light falling on his subject. Corrections are then made by means of color compensating (CC) filters. (Color temperature meters are not to be confused with light meters. They do not indicate the brightness level of the light source.) There are two such meters manufactured. One is the Eastman Kodak color temperature meter. The other is the Harrison light corrector. While color temperature meters are designed primarily for measuring the color temperature of tungsten or Photoflood light sources, they can be used effectively for exterior daylight shooting. The meter is capable of measuring sunlight or daylight illumination when the color temperature does not exceed 6500° or 7000° K. Beyond this range, the meter tends to lose its effectiveness because of the predominance of ultraviolet rays, which cannot be measured accurately by the instrument beyond a certain point. However, the color temperature meter can be employed effectively to measure the approximate departure of the color of daylight from that corresponding to the color temperature for which the film is balanced. The Eastman Kodak color temperature meter. The Eastman Kodak color temperature meter is an instrument relatively easy to operate. It consists of a rotating scale containing a divided disc of graduated spectrum colors. The meter reads the reflected light of the source being measured. A white card held in front of the meter is used to reflect this light through the meter's graduated color disc. As the light is viewed through the meter, this color disc is rotated slowly until colors of both halves of the divided scale match identically in hue. When this has been accomplished, you have an approximate color temperature reading of that light source. The results of this reading are clearly indicated in Kelvin degrees on the meter dial. From this reading you can determine the proper color compensating filter, if any, to be used. Should your reading indicate that the light source is off balance, you should set your meter dial at the given Kelvin rating of your film. As an illustration, let us say that you are using Kodachrome Type A (which we know has an approximate balance of 3400° K) and Photoflood illumination. If your original reading showed that the light source was off balance, set the scale of your meter at the known film balance of 3400° K and select from your set of color compensating filters the ones that should return your color balance. When the temperature of the light is lower than the film balance permits, a bluish filter should be selected. When the temperature is higher, a yellowish filter must be used. Maintaining your meter at 3400° K, the selected filters are held separately over the meter objective, pointed at the light source. When the meter balance is restored, that is the correct filter to use over your camera lens. In some instances, it may be necessary to combine two CC filters to restore your color balance. However, this procedure is not recommended except in extreme cases. Until you are thoroughly familiar with the operation of the meter, it is suggested that you take several readings, to avoid possible errors. With experience gained by using the color temperature meter, it will be possible to read the temperature of an artificial light source to an accuracy of less than 50° deviation, which is close enough for practical use. 100° deviation is considered the maximum acceptable variant. One advantage of the Eastman meter is that the manufacturer has recognized an important weakness of such an instrument, which is the human variation of individual color response. It is known that a wide range of color perception exists among different people, and sometimes between two eyes of the same person. Eastman has made possible the adjustment of their meter to this individual color response of the user. [Continued on page 74] Lloyd W. Durant f \ OttMIH'11™ CO* . ,>uiM C&-/ST C010R COMPENSATING GIUTINBliK • The Eastman Kodak color temperature meter, which, as well as the Harrison color corrector, aids amateur filmers in controlling color temperature.