PHOTOMETRY, BEAM, COLOR & UNITS
Candela measures luminous intensity — how much light a source throws in a given direction. Work it out from a measured lux level and distance, or estimate it from lumens and the beam angle.
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Luminous intensity (candela)
From lux: candela = lux times distance squared. From lumens: candela = lumens divided by the beam solid angle.
Two ways to find candela
If you know the illuminance at a point, the inverse-square law rearranges to candela = lux times distance squared. If you know the lumens and beam angle, candela equals lumens divided by the beam solid angle, where the angle sets how tightly the light is focused.
Narrower beam, higher candela. The same lumens packed into a tighter beam angle produce far more candela — and a brighter, more focused pool of light.
See the Luminous Intensity Formula and the Inverse Square Law.
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