Light and Photography

A candle's light and daylight differ greatly in brightness and in their color. Imagine looking at a single lighted candle in a dark room and then opening a large window, allowing daylight to pour into the room. Within seconds your eyes adjust to the brightness and blue color of the daylight and everything looks "normal." Now close the window and, in the dark room, look at the candle. Its light will now appear unusually orange. Again, within seconds, your eyes will adjust and the darkness won't seem so dark and the orange candlelight will appear white.

Neither the daylight nor the candlelight is neutral white light. The daylight is too blue and the candle is too orange. They both appear neutral because our vision system has the extraordinary ability to adjust to the variations in brightness and color of most light sources. In fact, our brain constantly makes adjustments to insure we perceive what appears to be neutral, white light. These visual adjustments happen automatically just like our breathing.

Film does not have our brain's ability to adjust. Motion picture films are manufactured to be compatible (or balanced) with only two light sources. Indoor, or tungsten balanced film, is manufactured to see 3,200 K light as "normal." Outdoor, or daylight balanced film is manufactured to see 5,600 K light, as "normal." Any other combination of film and light source will change the color of the scene on film. To the human eye, both types of light look neutral because we can adjust, but film has no ability to adjust on its own.

With this arrangement, the color rendition on film will be accurate. The color temperature of the film in the camera matches or balances the color temperature of the light. The color rendering on film will look normal.

The color will remain accurate here because the film in the camera matches or balances the color temperature of the light source. The color rendering on film will be normal.

Here, the scene is outdoors in 5,600 K sunlight but with 3,200 K film in the camera. The picture will have a blue cast because the 5,600 K sunlight has a higher color temperature (bluer) than the 3,200 K light that the film is manufactured to see as normal.

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With the mismatch reversed, the 5,600 K film and a 3,200 K light source will result in an orange cast to the picture's color. The light source has a color temperature lower (redder) than the color temperature of the 5,600 K film stock.

There's a simple solution to the imbalance of lighting and film color temperatures. A filter can be added to the camera lens or the light source. The filter will change the color temperature of the light that strikes the film.

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Here, an actor stands outdoors in 5,600 K sunlight. There is 3,200 K film in the camera. Shooting under these conditions will make the color on film too blue. Since the sunlight is too blue, a filter can be used to remove some of that blue light. On the subtractive color wheel, yellow is opposite blue (complementary color). Placing an orange-shish-yellow filter (commonly called an 85B filter) over the camera lens will absorb a portion of its complementary color (the o unwanted blue light) and effectively lower the color temperature of the sunlight to 3,200 K.

This will balance the light source and the film. A filter absorbs its complementary color. It is subtractive because it absorbs or removes wavelengths of light. To compensate for this loss of light, the lens aperture must be opened up two-thirds of a stop (with an 85B filter) for proper exposure.

Videotape or digital storage media has no color temperature rating, but a video camera's electronics do. By activating the white balance on a camera, its electronics will compensate and make the incoming light appear neutral and white. Some video cameras can automatically white balance by reading the ambient light coming into the lens and instantaneously adjusting the video system's electronics.

Matching the color temperature of the film and light source is common practice; however, there are many times when an imbalance of the two is intentional. You might want your pictures to be too blue or orange, and so a mismatch of light and film will quickly achieve your goal. Any color shift may be artistically correct even though it's a technical mismatch between the light source and the film's color temperature. The only correct color is the color you want for your final production.

Many photographers mix color temperatures to create a more natural or varied look for a scene. In the real world we mix color temperatures all the time. A room, for example, may be lit with daylight coming though a window and a 60 watt reading lamp. We may not notice the color differences as quickly as we do on a screen, but multiple color temperatures can produce a wide variety of visual styles.

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