CANDELA to LUMEN Conversion

Luminous Intensity = 2700 cd (Candela)Beam Angle = 36 ° (12°, 24°, 36°, 60°)

1 lumen = 1 candela·steradiansr = 2 π (1 - cos(θ/2))

Lumen (lm) = candela · steradian= cd * 2 * π * ( 1 - Cos (θ/2) )

= 2,700 * 2 * π * ( 1 - Cos ( 36 °/2) )

= 5,763 lm

where sr is the solid angle in steradians, and θ is the beam angle.

Glossary

Beam AngleAny directional lamp emits light energy in the shape of a cone. 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. The usable portion of the cone is defined at the point where theCandlePower falls to 50% of the CandlePower at the center. Our eyes perceive this portion of the lamps cone as one intensity of light even though, at itsedges, the intensity has dropped to half. This portion of the total cone of light is termed the Beam Angle.

It is the Beam Angle we are concerned with when it comes to spacing one directional lamp to another.

The Beam Angle is found in the lamp manufacturers' 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. 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. Any ofthese listings refer to the lamp CandlePower and are considered to be the same.

CandlePower is used in the Inverse Square Law calculation.

Some texts indicate that 1 candela = 12.57 lumens; do not try to convert lumens to candelas using this formula. Results will be inaccurate.

Candela See CandlePower.

CandlePower

Any directional lamp emits light energy in the shape of a cone. 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. The usable portion of the cone is defined at the point where theCandlePower falls to 50% of the CandlePower at the center. Our eyes perceive this portion of the lamps cone as one intensity of light even though, at itsedges, the intensity has dropped to half. This portion of the total cone of light is termed the Beam Angle.

It is the Beam Angle we are concerned with when it comes to spacing one directional lamp to another.

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. 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. Any of

Some texts indicate that 1 candela = 12.57 lumens; do not try to convert lumens to candelas using this formula. Results will be inaccurate.

75W Halogen (BLV)

50W Halogen (OSRAM)

degrees radians spherical solid angle planar solid angle Degree5 0.087266463 0.0059802 0.005981149 510 0.174532925 0.023909417 0.023924596 1015 0.261799388 0.053753521 0.053830341 1520 0.34906585 0.095455703 0.095698385 2025 0.436332313 0.14893658 0.149528726 2530 0.523598776 0.214094348 0.215321366 3035 0.610865238 0.290804975 0.293076303 3540 0.698131701 0.378922439 0.382793539 4045 0.785398163 0.478279003 0.484473073 4550 0.872664626 0.588685536 0.598114905 5055 0.959931089 0.709931873 0.723719035 5560 1.047197551 0.841787214 0.861285463 6065 1.134464014 0.984000567 1.01081419 6570 1.221730476 1.136301218 1.172305214 7075 1.308996939 1.298399256 1.345758536 7580 1.396263402 1.469986118 1.531174157 8085 1.483529864 1.650735177 1.728552076 8590 1.570796327 1.840302369 1.937892293 9095 1.658062789 2.038326841 2.159194807 95100 1.745329252 2.244431642 2.39245962 100105 1.832595715 2.458224441 2.637686731 105110 1.919862177 2.67929827 2.894876141 110115 2.00712864 2.907232302 3.164027848 115120 2.094395102 3.141592654 3.445141853 120125 2.181661565 3.381933205 3.738218157 125130 2.268928028 3.627796454 4.043256758 130135 2.35619449 3.878714388 4.360257658 135140 2.443460953 4.134209368 4.689220856 140145 2.530727415 4.393795046 5.030146352 145150 2.617993878 4.656977286 5.383034146 150155 2.705260341 4.923255105 5.747884238 155160 2.792526803 5.192121629 6.124696628 160165 2.879793266 5.463065054 6.513471317 165170 2.967059728 5.735569625 6.914208303 170175 3.054326191 6.009116613 7.326907587 175180 3.141592654 6.283185307 7.75156917 180185 3.228859116 6.557254001 8.188193051 185

Radians0.0872665 11.3169190.1745329 4.5008830.2617994 4.1052110.3490659 11.5552270.4363323 0.0138340.5235988 11.0564450.6108652 4.9044030.6981317 3.7191300.7853982 11.7703200.8726646 0.0552740.9599311 10.7749531.0471976 5.3139951.1344640 3.3443391.2217305 11.9612511.3089969 0.1241391.3962634 10.4736811.4835299 5.7278541.5707963 2.9824901.6580628 12.1271791.7453293 0.2201251.8325957 10.1539561.9198622 6.1441592.0071286 2.6351752.0943951 12.2673732.1816616 0.3428092.2689280 9.8171872.3561945 6.5610762.4434610 2.3039232.5307274 12.3812162.6179939 0.4916512.7052603 9.4648562.7925268 6.9767692.8797933 1.9901942.9670597 12.4682063.0543262 0.6659963.1415927 9.0985153.2288591 7.389408