White Balance

The color of light is described as the “color temperature”, which is measured in the Kelvin scale of absolute temperature. In photography, the color temperature refers to the wavelength of that particular color. The higher the color temperature (up to about 11,000˚K) the more blue the light. The lower the color temperature (down to about 1900˚K) the more red the light. Those of you who have experience with color film probably know that “daylight” falls in the middle of the scale, at 5500˚K.

Although people generally perceive colors accurately regardless of the lighting situation, this is not true of film and digital sensors. When daylight balanced film or a digital sensor set to be used under daylight is used in a different lighting situation, such as incandescent, or fluorescent light, a colorcast will occur. A daylight setting used under incandescent light will produce an orange cast. A daylight setting used under fluorescent light will produce a yellow-green cast. A photographer using a film camera would use a filter to correct for this “chromatic aberration”. This is not necessary with most digital cameras, as they allow you to change something called the “White Balance”. This is the digital equivalent to using an external filter. Instead of the Kelvin scale, lighting situations are referred to as “cloudy”, “overcast”, “daylight”, “fluorescent”, “tungsten (incandescent)”, etc. Normally the camera is set to “Auto White Balance”, but most digital cameras will allow you to set the white balance for specific types of lighting situations. This will neutralize the colorcast that would otherwise occur.