what is the difference between LUMENS and CANDLE POWER?

Answer 1

Candle power obviously denotes the power of the light source, ie how many lumens it emits.

Lumens measure the amount of light a source emits.
1 candle = 4 pi lumens

So you meet expressions like this: This light source has a power of 10 candles and (therefore) emits 126 lumens.

The brightness of source is measured in lumens per cm2

The efficiency of an electric light source is measured in lumens per watt..

Answer 2

Lumens define an intensity of light at a particular distance. When a bulb is rated for lumens, that's the total amount of light it produces.

Candlepower is measured as the amount of light, or brightness, incident at a point. So it doesn't measure the total light put off by a bulb, but the brightness at some point they measure.

Household electric bulbs, like incandescents and fluorescents, are usually rated in lumens, or total light output. Flashlights tend to use candlepower. This can often be misleading, because they use the reflector to concentrate the light of the bulb, and if they focus the reflector very close and measure the light intensity at, say, one inch from the bulb, they can come up with very high candlepower ratings for relatively not so-bright bulbs. They can optimize the design of a flashlight to come out high on the candlepower test, which actually makes it a less good light for regular use.

The relationship between candlepower and lumens is defined:

"If a light source emits one candela of luminous intensity into a solid angle of one steradian, the total luminous flux emitted into that solid angle is one lumen." - From Wikipedia.

Answer 3

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*A LUMEN is a unit of measurement of light. It measures light much the same way. Remember, a foot-candle is how bright the light is one foot away from the source. A lumen is a way of measuring how much light gets to what you want to light! A LUMEN is equal to one foot-candle falling on one square foot of area. Candlepower is a way of measuring how much light is produced by a light bulb, LED or by striking an arc in a Carbon-Arc spotlight. Is it a measure of how much light falls upon an object some distance away? No. That's illuminance. Is it a measure of how well we see an object that is illuminated by that light source? No. That's something all together different, and we are not going there! Nowadays we use the term CANDELA instead of candlepower. Candlepower, or CANDELA is a measure of how much light the bulb produces, measured at the bulb, rather than how much falls upon the thing you want to light up. Further confusing the matter is beam focus. That's how much candlepower can be focused using a reflector/lens assembly. Obviously, if you project all your light bulbs intensity at a given spot, or towards something, it will be more intense, and the illuminance will be higher. And here comes the confuser! A candlepower as a unit of measure is not the same as a foot-candle. A candlepower is a measurement of the light at the source, not at the object you light up. And a candela is the metric equivalent of the light output of that one candle, based on metric calculations. And since using a candle is rather imprecise, the definition was amended to replace a light source using carbon filaments with a very specific light source, see the following: The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 x 1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian. *Candlepower is a measure of light taken at the source-not at the target. Foot-candles tell us how much of that light is directed at an object we want to illuminate. *LUX is an abbreviation for Lumens per square meter. Foot-candles equal the amount of Lumens per square feet of area. So, that one candlepower equivalent equals 12.57 lumens.

Answer 4

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what is the difference between LUMENS and CANDLE POWER?

Answer 5

A lumen AKA foot-candle is the unit of measurement of light. One lumen equals the amount of light received from one candle one foot away, ten lumens = ten candles, and so on. Candle power is a way of indicating how many lumens of light something gives off.

Answer 6

Divide the number of lumens you have produced, or are capable of producing, by 12.57 and you get the candlepower equivalent of that light source.