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  1. #1

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    Red LED's for darkrooms

    I talked to a guy, who is doing some scientific work with LED's....
    I asked him witch LED's would be the best to use in a darkroom.....
    And he ask me what kind of light is enlargement paper NOT sensitive towards...
    And that is the question: Where do I find this information ????
    It have to be something about nanometers (He used that word) i.e. something to do with wavelength of the light, witch the enlargement paper can 'take'...
    And an other question: At which wavelength are the enlargement paper most sensitive.... Perhaps it would be possible to use LED for contact copies....and enlargement....
    It might be dependent of what brand one use....

    Niels-Erik
    Last edited by Erik Hartmann; 12-20-2007 at 03:40 PM. Click to view previous post history. Reason: Very bad spelling

  2. #2
    Dave Miller's Avatar
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    This has been discussed many times Erik, I suggest a thread search for LED will provide information.
    Regards Dave.

    An English Eye


  3. #3

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    OK I tryed Dave.... When I search LED I had about 100 hits...... with much else than LED......
    That why I put the question up here....

    niels-erik

  4. #4
    Bob F.'s Avatar
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    Searching on LED SAFELIGHT gives a more specific set of results:

    http://www.apug.org/forums/forum37/4...afe-light.html and http://www.apug.org/forums/forum41/3...materials.html are possibly the most relevant and recent. Most of the threads on safelights in general will have posts about using LEDs too.

    Bottom line is that any red LED will be fine, as will most orange LEDs. By the time you get to amber you are entering into the range where b&w paper is starting to get sensitive to that colour light so need to be more careful. Most VC papers are pretty insensitive above 580nm (amber) - many graded are insensitive much above 525nm. As a general guide, red is up at 650nm. I generally use orange as I find red too depressing and messes with my eyes... In any event, always test your safelight and paper combination - even a deep red LED will fog paper eventually if too bright.

    Manufacturers' data sheets for their papers invariably show their response to light across the spectrum and can be downloaded from their web sites.

    Cheers, Bob.

  5. #5
    MattKing's Avatar
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    As an example, on the Harman/Ilford site, if you go here to the Technical Specifications link:

    http://www.ilfordphoto.com/products/default.asp

    and then click on the photographic papers link:

    http://www.ilfordphoto.com/products/...graphic+Papers

    You can choose which paper you are interested in, and the corresponding pdf will have the information.

    Matt

  6. #6

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    Thans Bob and Matt.....and Dave off course.....
    I tink I got all I needed to go on with my scientific connection....
    If he commes up with some new things, I will put it up here......

    Thanks and Happy Holiday's

    Niels-Erik



 

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