Light—Science & Magic- P7

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Light—Science & Magic- P7 LIGHT—SCIENCE & MAGIC 10.8 Holding the flash high enough causes many distracting shadows to disappear. Photographers working on location may not be able to care- fully control the color temperature of the light. The existing light in the scene often does not match any standardized photographic color balance. It may be impossible to get rid of the existing light. Even in an indoor location in which the existing light can be turned off, it may be essential to leave it on for enough light to illuminate a large area. This nonstandard color has unpredictable consequences if photographers do not anticipate problems and take steps to deal with them. Why Is the Color of the Light Important? Shooting a color image with light sources of different colors can be a serious problem. When we look at a scene, our brains compensate for some fairly extreme differences in the color of light to interpret most scenes as lit by “white” light. There are exceptions to this: if you are traveling at dusk, with your vision 288 TRAVELING LIGHT adjusted for dim daylight, you can see the lights of a distant house to be the orange color that they really are. If you stop at that house, however, and go in, your brain will immediately compensate again and you will see the light as white. To see why, let’s look at the two standard light colors, tungsten and daylight. Tungsten. This applies to a scene illuminated by tungsten bulbs. These tend to be relatively orange. Set for tungsten, the camera white balance compensates for the orange. Used with tungsten lights, it produces picture colors that are close to natural. If, however, we were to use a tungsten white balance to shoot a picture illuminated by daylight, the resulting color would be nonstandard. Instead of looking “normal,” the entire scene would appear very blue. To be accurate, we have to point out that household tungsten bulbs almost never produce light that is the color of photographic-standard tungsten. They are more orange when they are new and get still more orange with age. Quartz-halogen lights, used by photographers and theater producers, do have accurate tungsten color and keep that accurate color through the duration of the life of the lamp. Daylight. Daylight white balance produces standard color in a scene that is illuminated by the sun. Obviously, sunlight is different colors at different times of day and in different weather conditions. Originally “standard daylight” was sun- light, at a specific time of day, at a specific time of year, at a specific location, and on a cloudless day, in Britain. Such light is rich in blue, and that is why the sky on a clear day is blue. A daylight color balance compensates for this and gives the most accurate color reproduction used with either mid-day sunlight daylight or strobe. If this bal- ance is used with tungsten light, the pictures look orange. Nonstandard Light Sources Photographers consider daylight and two slightly different colors of tungsten light to be “standard.” All of the others are nonstandard to us. Unfortunately, “nonstandard” does not mean “unusual” or “rare.” Other lights are quite common. We will use a few of them as examples. This does not approach a complete list of nonstandard sources, but they show the 289 LIGHT—SCIENCE & MAGIC dangers well enough to keep you alert to the potential problem in any location assignment. The frequent mix of lighting, especially in many modern offices, is the root of the problem. The digital camera can com- pensate for the color of almost any nonstandard light. Furthermore, it can compensate for almost any even mix of light colors. The difficulty comes from an uneven mix: part of the scene is lit by one light, and other areas are lit by lights of other colors. It’s expecting too much to want the camera to fix such problems, and we have to think better than the camera does to fix them ourselves. Following are some common non- standard light sources. Fluorescent tubes are the nonstandard light source photog- raphers encounter most frequently. The light produced by flu- orescent tubes presents photographers with a special problem. In addition to being nonstandard, it comes in many different colors. Age changes the color of fluorescent tubes slightly. Furthermore, people replace burned-out tubes with new ones of another type. After a few years, a single large room may have several different types of tubes. A white balance that is good for any particular type of tube may be bad for the rest. As a rule, the light from these tubes tends to have a strong green cast. This can produce some particularly unpleasant non- standard colors when either tungsten or daylight film is used. People, in particular, tend to look awful when they are pho- tographed under uncompensated fluorescent lighting. Nonstandard tungsten light is more common than either of the photographic standard tungsten color temperatures. Ordinary tungsten bulbs are significantly more orange than photographic bulbs, and they get more so as they age. ...