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A foot-candle (sometimes foot candle; abbreviated fc, lm/ft 2, or sometimes ft-c) is a non-SI unit of illuminance or light intensity. The foot-candle is defined as one lumen per square foot. This unit is commonly used in lighting layouts in parts of the world where United States customary units are used, mainly the United States. [1]
Illuminance diagram with units and terminology. In photometry, illuminance is the total luminous flux incident on a surface, per unit area. [1] It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. [2]
The American Society of Cinematographers (ASC) defines lighting ratio as (key+fill):fill, or (key+Σ fill):Σ fill, where Σ fill is the sum of all fill lights. Light can be measured in footcandles. A key light of 200 footcandles and fill light of 100 footcandles have a 3:1 ratio (a ratio of three to one) — (200 + 100):100.
A foot-lambert or footlambert (fL, sometimes fl or ft-L) is a unit of luminance in United States customary units and some other unit systems. A foot-lambert equals 1/π or 0.3183 candela per square foot, or 3.426 candela per square meter (the corresponding SI unit).
The corresponding unit in English and American traditional units is the foot-candle. One foot candle is about 10.764 lx. One foot candle is about 10.764 lx. Since one foot-candle is the illuminance cast on a surface by a one-candela source one foot away, a lux could be thought of as a "metre-candle", although this term is discouraged because it ...
At the time the UK established candlepower as a unit, the French standard of light was based on the illumination from a Carcel burner, which defined the illumination that emanates from a lamp burning pure colza oil (obtained from the seed of the plant Brassica campestris) at a defined rate. Ten standard candles equaled about one Carcel burner.
In lighting design, the lumen method, (also called zonal cavity method), is a simplified method to calculate the light level in a room.The method is a series of calculations that uses horizontal illuminance criteria to establish a uniform luminaire layout in a space.
Daylight harvesting systems are typically designed to maintain a minimum recommended light level. [1] This light level will vary according to the needs and use of the space; for example, the commonly recommended light level for offices is 500 Lux (or around 50 foot-candles) on the desktop.