Convert between footcandles and other major units of illuminance.
A unit of illuminance in the foot-pound-second system of units, the illuminance at 1 foot from a 1-candela point source of light. Symbol, Ftc. One footcandle is approximately 10.76391 lux.
Originally the footcandle was the illuminance at 1 foot from a standard candle, then at 1 foot from an international candle. It was next defined as the illuminance produced by 1 lumen of “luminous flux” evenly distributed over a square foot.
Though not an SI unit, footcandles are still widely used to set lighting levels in architecture, in stage lighting, and in photography.
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Last revised: 13 September 2011.