Technical Lighting Terms
Daylight: - Combination of direct sunlight and skylight. Best light for optimal color rendering.
Beam Spread: - Refers to the divergence angle of the light exiting the lamp. The smaller the number, the tighter and brighter the beam.
Candle Power - Used by lighting designers to calculate the foot-candles illuminating a surface (C.P. /distance in feet squared) or Lux illuminating a surface
(C.P./distance in meters squared).
Correlated Color Temperature (CCT) - refers to the apparent color of the light source. 2800K – 3200K considered “warm” ; 4100K-4900K considered “white” and 5000 K
+ “cool”. Comes from heating a blackbody (think of a piece of coal) up to a certain temperature; as the coal gets hotter and hotter, it changes from orange (i.e., 2300 K)
to yellow (3000 K) to white (4700 K) to blue (5000 K). rendering.
Color Rendering Index (CRI) - Measure of how well a light source replicates a
given lighting condition; 100 being perfect, 90 fair, 80 poor.
Foot-candles - Measurement of light output in candelas per square foot. 100-foot candles is generally considered enough light to perform most tasks.
Infared Radiation (I.R) - Associated with sunburns and heat. Lower energy, long wavelength energy situated at the red end of the visible light spectrum.
Lumen - Measurement of a quantity of light as perceived by the human eye. As a light source’s color temperature increases, less light is required to achieve comparable brightness and visual acuity.
Lux - Measurement of light output in candelas per square meter. 10 lux is generally
Considered enough light to perform most tasks.
Ultraviolet Radiation (U.V.) - Associated with suntans and fading of pigments and dyes. High-energy short wavelengths before the blue end of the visible light spectrum.
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