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Thread: candlepower vs lumens

  1. #1

    Default candlepower vs lumens

    How do you, or do you, measure lumens from a known/published candlepower??

  2. #2
    Flashaholic* Oddjob's Avatar
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    Default Re: candlepower vs lumens

    Welcome to CPF. Next time you accidentally post in the wrong forum just notify a moderator and ask them to move it to the correct one rather than starting a new one. As for you question, I do not know but someone here might.
    I'd rather have it and not need it than need it and not have it.

  3. #3
    *Flashaholic* Marduke's Avatar
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    Default Re: candlepower vs lumens

    You cannot convert candlepower or lux into a measure of lumens.

    They measure two completely different things.

  4. #4

    Default Re: candlepower vs lumens

    OK, so a light with published candlepower (80000) and no lumens would need to be scientifically tested for a lumens rating?

  5. #5
    *Flashaholic* Marduke's Avatar
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    Default Re: candlepower vs lumens

    Quote Originally Posted by trapperjay View Post
    OK, so a light with published candlepower (80000) and no lumens would need to be scientifically tested for a lumens rating?
    Yes, or theoretically calculated based off other values not related to candlepower.

  6. #6
    *Flashaholic* kramer5150's Avatar
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    Default Re: candlepower vs lumens

    Quote Originally Posted by trapperjay View Post
    How do you, or do you, measure lumens from a known/published candlepower??
    There is no conversion... they quantify two completely different elements.

    Lux = the light intensity at a given point infront the of the source.
    Lumens = the total amount of light emitted from the source.

    I don't think there is a conversion between Lux and candlepower
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  7. #7
    Flashaholic
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    Default Re: candlepower vs lumens


  8. #8
    Flashaholic
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    Default Re: candlepower vs lumens

    You might be able to guestimate: (and see the online convert link warnings).

    http://en.wikipedia.org/wiki/Candela
    [...]
    Relationship between luminous intensity and luminous flux
    If a source emits a known intensity (in candelas) in a well-defined cone, the total luminous flux in lumens can be calculated by taking the number of candelas, and dividing it by the number in the table below that corresponds to the "radiation angle" of the lamp (the full vertex angle of the emission cone). See MR16 for emission angles of some common lamps. Theory Formulas Online converter
    • Example: A lamp that emits 590 cd with a radiation angle of 40į:
      590/2.64 = approximately 223 lumens.
    [...]

  9. #9
    *Flashaholic* kramer5150's Avatar
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    Default Re: candlepower vs lumens

    Quote Originally Posted by Twinkle-Plank View Post
    ... lumens per square foot... I think thats different than total emitted lumens
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  10. #10
    Flashaholic* Search's Avatar
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    Default Re: candlepower vs lumens

    You could convert lux to lumens. It would be extremely complicated but think about it.

    If you took a flashlight and shined it on a wall five meters away one spot could have a lux of 5000.

    The light could be 100 lumens.

    You could find a formula to convert this.

    However, you would have to have a new formula for every flashlight because they all have different beam profiles.

    Another light could have a lux of 10000 but only 80 lumens.

    Another could have a lux of 5000 but 160 lumens.

    One would be a little throwy and the other floody.

    It would be complicated.

    Better to keep them two separate entities without being able to be converted.

    Lumens tells you how much light a flashlight produces and lux tells you how the beam profile is in a general idea.

    Depends on how bright the spot is compared to the spill.


  11. #11
    HKJ's Avatar
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    Default Re: candlepower vs lumens

    Quote Originally Posted by Search View Post
    You could convert lux to lumens. It would be extremely complicated but think about it.
    Not really, lumen is lux * area

    To do it:
    Paint a lot of small squares on a wall
    Shine a light on the wall
    Measure the lux in each square
    Sum the lux*square size for all the squares and you have lumens
    Expect rather large tolerances, lux meters are not very exact.

    This could be optimized, as long as you have some symmetry in the beam.

  12. #12
    Flashaholic* Juggernaut's Avatar
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    Default Re: candlepower vs lumens

    I find it easy if your talking about an Incan you can just find the Lumens to watts of that bulb and then multiply by itís wattage, thatís how I find the output of Incans, if there is a light you want me to tell you how bright it is just give me itís statistics.
    ďWhat do you mean LEDs are more efficient then Incans?Ē, thatís just what they want you to think! Itís a Conspiracy, Man!

  13. #13

    Default Re: candlepower vs lumens

    In short, no you can't accurately convert one to the other or vice versa... Here's a good read about Candlepower vs. Lumens. Hope that helps!

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