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Thread: How many lumens from a candle?

  1. #1
    Flashaholic* Phaserburn's Avatar
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    Default How many lumens from a candle?

    of the taper variety; the ultimate incandescent! Just curious how a candle stacks up to various flashlight outputs.

  2. #2
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    Default Re: How many lumens from a candle?

    [ QUOTE ]
    Phaserburn said:
    of the taper variety; the ultimate incandescent! Just curious how a candle stacks up to various flashlight outputs.

    [/ QUOTE ]

    It will of course vary with wick length, wax type, and probably other factors but it likely will fall in the 5 to 15 lumen range. The bureau of standards folks used to have a description of the construction of the "standard candle" from which intensity measurements were defined before they went to the definition using the black body cavity radiation involving a temperature defined by the melting temperature of platinum. If you search around you may find a description of that "standard candle".

  3. #3
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    Default Re: How many lumens from a candle?

    A standard candle is defined as giving off one candlepower over 4*pi steradians. Even you do the math, this comes to 12.56636 lumens.

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    Default Re: How many lumens from a candle?

    [ QUOTE ]
    jtr1962 said:
    A standard candle is defined as giving off one candlepower over 4*pi steradians. Even you do the math, this comes to 12.56636 lumens.

    [/ QUOTE ]

    Actually not true. The physical candle used for the standard for candlepower [a unit of intensity] was not an isotropic source. The candlepower was defined along a horizontal axis relative to the wick. jtr1962 is thinking of the unit Mean Spherical Candle Power [MSCP] another old unit that was in fact 4*pi lumens. The physical candle from which the intensity unit candlepower is derived would have emitted somewhat less than 4*pi lumens.

  5. #5
    *Flashaholic*
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    Default Re: How many lumens from a candle?

    Actually, MSCP was what I meant. I wasn't referring to a physical candle in my post, just to the derivation of the unit candlepower. I know they're not uniform in their illumination.

  6. #6
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    Default Re: How many lumens from a candle?

    BTW, if you want to build one of these candle standards at home, start by harpooning a Sperm Whale. The candle definition includes "constructed so as to burn 7.8 grams per hour of spermaceti..."

  7. #7

    Default Re: How many lumens from a candle?

    What about the parrifin wax and lox they are experimenting with for rocket fuels? how many candlepower does that put out i wonder. =(

  8. #8
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    Default Re: How many lumens from a candle?

    Mark's Standard Handbook for Mechanical Engineers (10th Edition) page 12-99 defines "candela, cd (formerly candle) is the unit of luminous intensity of a light source. One candela is defined as the luminous intensity in a given direction, of a source that emits monochromatic radiation of a frequency 540 x 10(12)HZ (approx. 55 nm) and of which the radiant intensity in that direction 1/683 W per steridan (W/sr)." It goes on to show in table 12.5.1 that a single candle flame is rated at 6.45 cd/in2.

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