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Kelvin and Nanometers

Discussion in 'Indoor Growing' started by rkm, Jan 21, 2008.


    rkm Well-Known Member

    Can someone tell me if there is a relation between Kelvin and Nanometers? Meaning, can the two be converted into each other? If so, what would a 2700K convert to in nanometers. I am thinking the two are totally different but hell, had to ask.

    snaggy Active Member

    Good question I would also like to know.

    There has to be a relation, otherwise how would plants grow under LED and nm alone, or CFL, HID & kelvin alone.
    Yet I cannot find any substantial facts anywhere on the net with the relation of the two.
    In a CFL post I was asking for a CFL kelvin/nm chart of the most common cfl spectrums.
    You would figure if the manufacturers hardware really works, they would want to show you its performance.
    Or even astronomer's with a season sun kelvin/nm chart.

    Here mentions abit of the relationship nm and kelvin.......Yet I cannot make shit of their graph charts to understand it.
    The Double Amici Prism Hand-Held Spectroscope

    Would sure be good to see some real substantial grapgh charts in relation to kelvin and nm.

    mdgtptrl Well-Known Member

    here's the kelvin scale:

    and here's a wavelength scale:

    match color to color and you have kelvin to wavelength.

    Now, keep in mind that any light source (except LEDs) produces a broad spectrum... ie it's not JUST that one color. The color temperature of a bulb is basically the average color emitted and what we see with the naked eye, i believe

    edit: quick reference about the kelvin color temperature scale. The way it works is this: a black body at a given kelvin temperature (3000k, let's say), emits light of that color. You know how iron glows red when it's really hot? Similar idea.

    snaggy Active Member

    Thanks for the links.
    Here some more on kelvin spectrum and nlites spectrum tests.

    Man, I want a 11000k CFL !
    They are used for aquatic life.
    But the Actinic (11000k) spectrum looks super sweet, and the most cost efficient use of output energy of the bunch for vegging!

    Only available in linear tubes that I have found so far.

    Attached Files:


    mdgtptrl Well-Known Member


    rkm Well-Known Member

    I am hooking two sets up tonight.

    mdgtptrl Well-Known Member

    cool. keep us updated.

    moon47usaco Well-Known Member

    Everyone likes to talk about these nlites but i do not believe they exist... Where can you buy them... I sent 2 emails to almost all the links on the nlites sight asking where to order and still no response... =[

    lucindrea Member

    nm = 2,897,768 / K
    Diabolus Sonata

    Diabolus Sonata Member

    Ushio makes awesome 10,000 12,000 and 20,000 K bulbs fo the aquarium. In saltwater the carals grow awesome under 4500 with little color, 10,000K you get good growth and good color, 20,000K corals grow slower but have amazing colors. This is debated hard on fish boards tho so, its just what I noticed in my reef tanks. And yes K = NM on some scale.
    bob harris

    bob harris New Member

    I've used aquarium lighting both in veg and in flower to increase blue spectrum. They work great, but they are mh bulbs, and do produce significant heat.

    I have settled on led's as my supplemental source in flower. Much less heat to deal with. Much smaller fixtures. Much easier to move around to balance the added spectrum easily.

    CMH lighting is coming along, and it has a much better spectrum than HPS..check out CMH lighting on google..
    Placidus Magnus

    Placidus Magnus New Member

    Kelvins to nanometers

    Kelvin for light, is a measurement of the heat given off by ablack body, which relates to the spectrum of light given off. Nanometers are ameasurement of one specific wavelength of light (one specific color). Kelvin isa rating of all the colors existing in a light source, but it does give anindication of the nm peak within the spectrum.
    The conversion from nm to K is: nm =2,897,768 / K

    In this equation: nm = nanometers, or peak wavelength

    K = Peak temperature, in degrees Kelvin.

    2,897,768 = the number that needs to be in the equation according to some bigscience and math conference where a whole lot of nerds got together and decidedthings like the number that needs to be in that spot in the equation. I triedto understand it, but I don't know anything about math terminology and am notsmart enough to learn about it tonight before I respond to this, so I can'texplain why that number exists, only that it has to be there to complete theconversion.

    This equation is called Wien's law, and it is actually a lot more complex thanI'm making it here, but to use it properly would take more understanding than Ihave. This method is not as accurate as if you were to use the full equation,but it's so close that most people even simplify it further to nm = 3,000,000 /K, and still consider it accurate enough to be a practical reference tool.

    A few examples.

    A light bulb rated at 4500K translates to 644nm.

    644 (nm) = 2,897,768 / 4500 (K)

    A light bulb rated at 6500K translates to 446nm.

    446 (nm) = 2,897,768 / 6500 (K)

    A light bulb rated at 10.000K translates to 290nm.

    290 (nm) = 2,897,768 / 10,000K

    The sun puts out peak radiation at 5778K, which is approximately 502nm.

    502 (nm) = 2,897,768 / 5778 (K)

    Adversely, to convert the opposite direction, swap the position of the nm andthe K to look like:

    K = 2,897,768 / nm

    The response to your question would look like this: K = 2,897,768 / 450K = 6,439K


    Attached Files:

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