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Thread: Avg lux in sunlight?

  1. #1
    Flashaholic* Phaserburn's Avatar
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    Default Avg lux in sunlight?

    What is an average lux reading in direct sunlight on a clear day? Anyone know? I've seen many references to the color temp of sunlight, but not lux strength.

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    Flashaholic* MoonRise's Avatar
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    Default Re: Avg lux in sunlight?

    Clear sky luminance is about 5.16 cd/in2 (8 kcd/m2) with a color temp of 6000K. That is equivalent to 2332 lumens/ft2, or 25,101 lumens/m2 which is 25,101 lux. (lux is lumen/meter2).

    Shifting to photgraphy knowledge, since there are about 2-3 f/stops (each f/stop is a doubling of light) difference between direct sun and clear sky lighting, there would be about 100,000 to 200,000 lux.

    The sun puts out a LOT of light. Also some heat. [img]/ubbthreads/images/graemlins/smile.gif[/img]

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    Flashaholic* Phaserburn's Avatar
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    Default Re: Avg lux in sunlight?

    Found this, for your amusement:

    Outdoors Conditional Illumination

    (ftcd) (lux)
    Sunlight 10,000 107,527
    Full Daylight 1,000 10,752
    Overcast Day 100 1,075
    Very Dark Day 10 107
    Twilight 1 10
    Deep Twilight .1 1.08
    Full Moon .01 .108
    Quarter Moon .001 .0108
    Starlight .0001 .0011
    Overcast Night .00001 .0001

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    Default Re: Avg lux in sunlight?

    [ QUOTE ]
    MoonRise said:
    Clear sky luminance is about 5.16 cd/in2 (8 kcd/m2) with a color temp of 6000K. That is equivalent to 2332 lumens/ft2, or 25,101 lumens/m2 which is 25,101 lux. (lux is lumen/meter2).

    Shifting to photgraphy knowledge, since there are about 2-3 f/stops (each f/stop is a doubling of light) difference between direct sun and clear sky lighting, there would be about 100,000 to 200,000 lux.

    The sun puts out a LOT of light. Also some heat. [img]/ubbthreads/images/graemlins/smile.gif[/img]

    [/ QUOTE ]


    Does that mean that looking at the sun and looking at a 25,000 lux incan are about the same?

  5. #5
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    Default Re: Avg lux in sunlight?

    Nope, it means that looking directly at the sun would be equivalent to looking at a 100K-200K lux light.

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