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Thread: lumen meter?

  1. #1
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    lumen meter?

    Does anybody now what the real term for a lumen meter is?
    I can get a lux meter, but would rather have something that takes measurements in lumens..

  2. #2
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    Quote Originally Posted by Goldigger
    Does anybody now what the real term for a lumen meter is?
    I can get a lux meter, but would rather have something that takes measurements in lumens..
    Integrating Sphere
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  3. #3
    whs
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    Quote Originally Posted by Goldigger
    Does anybody now what the real term for a lumen meter is?
    I can get a lux meter, but would rather have something that takes measurements in lumens..
    Btw., these are too expensive for people who are not in research or in lamp manufacturing. A few thousand dollar/euro for the proper ones...

    I had a look for second hand ones some time ago Don't come up often, as you would expect. Perhaps DIY is a possibility (see enhydralutris.de)

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    yeah i found that out since posting... I might just settle for the lux meter..

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    I found an app for windows mobile devices, but it seams to peak at 867 lumens..so no good for my lights..

    Dont need it to be accurate..just need it to be able distinguish differences...like different optics etc..
    Last edited by Goldigger; 01-18-2011 at 04:34 PM.

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    Well, if you just need 'relative' readings and that's pretty well all you'll get even if you buy a 'proper' lux meter, then there's a cheap sensor you can probably use for relative measurements.... It's called a CDS sensor - cadmium sulphide. Of course these days the greenies will chase you down and kill you since the sensor contains - oh my god - CADMIUM....

    Anyhow, you can find them cheap in some places - EU probably has sent suicide squads out to remove them for over there. But they still exist and can be purchased.

    Here's a link that has some basic info on them:

    http://www.ladyada.net/learn/sensors/cds.html

    All you need is the sensor and a multimeter since it just outputs a resistance value that varies with light intensity.

    cheers,
    george.

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    Quote Originally Posted by Goldigger
    I found an app for windows mobile devices, but it seams to peak at 867 lumens..so no good for my lights..

    Dont need it to be accurate..just need it to be able distinguish differences...like different optics etc..
    That's easy. Take a carton box, cover the inside with white matte paper and leave a hole for the lux meter sensor cable and the light source.

    Here is a more expensive DIY:
    http://www.candlepowerforums.com/vb/...d.php?t=200334
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  8. #8
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    I bought one of those el cheapo ones from Deal Extreme. It gives a rough representation of light output with which to compare to those overpriced mass-produced lights on the market (the ones that cost $300+ dollars ) which really arenít as bright dollar per dollar as the homebrew setups people (including me) have been building.
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    Quote Originally Posted by Leopold Porkstacker
    I bought one of those el cheapo ones from Deal Extreme. It gives a rough representation of light output
    On the contrary, a luxmeter can only measure spot intensity. it cannot collect all of the output of a light. A 1000 lumens flood light would probably be "dimmer" (according to the luxmeter), and an aspherical 100 lumen thrower.

    IMHO the "milk carton" spheres are not accurate . Integrating spheres are expensive because of the coatings used inside them - also, they are spheres for a reason. You're better off comparing ceiling bounces, but that, too, is usually fairly inaccurate.

    also, make sure your luxmeter has a photopic response filter - no point in having the luxmeter more sensitive in wavelengths human eyes are not.

    -Craig

  10. #10
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    Like I said, it gives a rough representation of light output with which to compare with other mass-produced lights. To me, a rough representation is just fine. I am no algebra/triginometry math science NASA geek, so coarseness of data is just fine.
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