This portion of the total cone of light is termed the Beam Angle. Our eyes perceive this portion of the lamps cone as one intensity of light even though, at itsedges, the intensity has dropped to half. The usable portion of the cone is defined at the point where theCandlePower falls to 50% of the CandlePower at the center. As you might expect, the CandlePower intensity is the greatest at the center of the cone and it diminishes the closer it gets to the edge of the cone eventually, in theory, to zero. Results will be inaccurate.Īny directional lamp emits light energy in the shape of a cone. Some texts indicate that 1 candela = 12.57 lumens do not try to convert lumens to candelas using this formula.

Any ofthese listings refer to the lamp CandlePower and are considered to be the same.ĬandlePower is used in the Inverse Square Law calculation.

Confusion is caused for some when one manufacturer lists a lamps CandlePower as 'Center-Beam CandlePower' while another notes it as 'Mean CandlePower' while still another uses 'Candela' as the heading for the same information in their Lamp Data Chart. The unit for measuring the quantity or intensity of light energy emitted by a directional lamp (i.e., narrow spot, spot, flood, wide flood, etc.).CandlePower is expressed in Candelas. The Beam Angle is found in the lamp manufacturers' Lamp Data Chart. It is the Beam Angle we are concerned with when it comes to spacing one directional lamp to another.

Beam AngleAny directional lamp emits light energy in the shape of a cone.

Felix candela caluclations