PHOTOMETRY, BEAM, COLOR & UNITS
Lux is the metric measure of illuminance — how much light lands on a surface, in lumens per square meter. Calculate it from total lumens and area, or from a point source using candela and distance.
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Illuminance (lux)
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Foot-candles
Lumens method: lux = lumens divided by area. Point-source method: lux = candela divided by distance squared.
Two ways to find lux
For an area lit by known output, divide the delivered lumens by the area in square meters. For a single source aimed at a point, the inverse-square law gives lux as candela divided by the distance squared.
Lux to foot-candles. Divide lux by 10.764 to get foot-candles. So 200 lux is about 18.6 fc.
See the Lux Formula and the Recommended Lux Levels.
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