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Can someone tell me the relation or difference between lumens and candlepower?
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rlhess
Enlightened
Lumens=total light output
Candlepower (aka candela)=light output in a given direction
If a light evenly illuminates exactly one steradian (a solid angle where the surface area is the square of the radius--there are 4*pi of them in a sphere) with one lumen, it's brightness is one candela.
No, you cannot convert candela to lumens. Lumens are measured in an integrating sphere capturing all the light. Candela are measured with an illuminance meter (and adjusted for the distance measured using the inverse square law) at one point--usually the brightest.
The only way to compare lights is subjectively and DO NOT BELIEVE the manufacturer's published Candlepower numbers.
In this sense, I've come to the conclusion that Candlepower=candela*marketing_factor.
You may see a few comparative candela measurements at my Web site in my sig--or see even more measurements of other lights at the linked sites.
This discussion has been had many times here and you might want to search for the longer threads.
Cheers,
Richard
Candlepower (aka candela)=light output in a given direction
If a light evenly illuminates exactly one steradian (a solid angle where the surface area is the square of the radius--there are 4*pi of them in a sphere) with one lumen, it's brightness is one candela.
No, you cannot convert candela to lumens. Lumens are measured in an integrating sphere capturing all the light. Candela are measured with an illuminance meter (and adjusted for the distance measured using the inverse square law) at one point--usually the brightest.
The only way to compare lights is subjectively and DO NOT BELIEVE the manufacturer's published Candlepower numbers.
In this sense, I've come to the conclusion that Candlepower=candela*marketing_factor.
You may see a few comparative candela measurements at my Web site in my sig--or see even more measurements of other lights at the linked sites.
This discussion has been had many times here and you might want to search for the longer threads.
Cheers,
Richard
