ABSTRACT
Photographs are taken by the agency of light travelling from the subject to the photoplane in the camera. This light usually originates at a source outside the picture area and is reflected by the subject. Light comes from both natural and artificial sources. Natural sources include the sun, clear sky and clouds. Light is a specific region of the electromagnetic spectrum and is a form of radiant energy. With fluorescent lamps, which vary greatly in spectral power distribution, covering a wide range of correlated colour temperatures, the results given by two lamps of nominally the same properties may be quite different if used for visual colour matching or for colour photography. A localized colour imbalance may then appear in the photograph. Another example is the use of tungsten lamps fitted with blue filters to match daylight for fill-in purposes, where some mismatch can occur.
