Lighting is an essential element of video production. Like the human eye, video cameras need to have an adequate amount of light to produce an acceptable picture. The minimum amount of light that is necessary for the camera to function properly is called the base illumination level, or baselight. A foot-candle is the amount of light that radiates from a standard candle to a point one foot from the center of the flame. Lux are calculated in the same manner as foot-candles except that the calculation is metric: one meter replaces one foot in the formula. Light is measured with a light meter. Light meters can be used to measure the amount of light falling on a scene, called incident light, or the amount of light reflected off a scene, called reflected light. Physicists have demonstrated that visible light is really electromagnetic radiation that can be manipulated.