Candela

The term Candela (unit symbol cd) is used to describe the light intensity of a light source, i.e. the intensity of the light beam radiated by a light source in a particular direction. As against the Lumen, which is mainly used to specify the total brightness of a source of light, Candela describes only the quantity of light streaming in a defined area (the so-called dihedral angle). Just like the Lumen, this unit also takes into consideration the perceptive ability of the human eye for different wavelengths. 1 Candela approximately corresponds to the brightness of a household candle.