User Tag List

Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: Different color light from different manufacturers?

  1. #1
    Join Date
    Jul 2017
    Location
    Pennsylvania USA
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Different color light from different manufacturers?

    Has anyone here noticed that the same K bulbs from different manufactures look a little different in color? I installed new 2' and 4' GE fluorescent T8 bulbs in place of Sylvania's with the same K rating that are cross referenced as equivalents by our suppliers but the colors look a little different.

  2. #2
    Join Date
    Dec 2006
    Location
    Chapel Hill, NC
    Posts
    34,022
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    There is no standard for how the led's will look at a certain temp. Some mfgrs. use cool white & warm white instead of using the kelvin scale.
    They say I shot a man named Gray and took his wife to Italy
    She inherited a million bucks and when she died it came to me
    I can't help it if I'm lucky



  3. #3
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,251
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    180224-0757 EST

    DrShowman:

    To be expected.

    See https://www.amazon.com/EISCO-Resolut...re-bullets-btf

    See additional information and comments. I did not realize that moderately useful low cost units existed. I had been aware of low cost gratings.

    To looks at visible light color components you can use a prism or diffraction grating.

    At Amazon I believe this one has an internal scale
    https://www.amazon.com/EISCO-Premium...re-bullets-btf

    If you heat a material (blackbody), tungsten for example, then there is a continuous frequency spectrum of radiation starting a zero, increasing to a peak, and then decreasing. The hotter the material the higher is the frequency of the peak point. The temperature in Kelvin (relative to absolute zero) can be used to describe the color characteristics of the light source. This works well with incandescent objects.

    The color sensors in the eye are tuned to approximately red, green, and blue. The sensors in two different people may not and probably are not (I have never studied this) tuned to exactly the same frequencies. Further they are not a very narrow band filters.

    Fluorescent and LED light sources use chemical compounds called phosphors excited by ultraviolet light to produce light in the visible spectrum. These phosphors do not generate a continuous spread spectrum like an incandescent body.

    To generate something that the eye sees as white is done by using various combinations of appropriate phosphors. The color output is given some K rating based upon its approximation to an incandescent source. Two different people may not see a particular phosphor source the same because of differences in their eyes.

    Two different manufacturers of lights may not use the same mix of phosphors, and/or from batch to batch there may be differences.

    See
    https://en.wikipedia.org/wiki/Optical_spectrometer
    https://en.wikipedia.org/wiki/Fluorescent_lamp

    .

  4. #4
    Join Date
    Jul 2017
    Location
    Pennsylvania USA
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I asked about 2' and 4' T* fluorescent bulbs not LED's. Thanks anyway.

  5. #5
    Join Date
    Jul 2017
    Location
    Pennsylvania USA
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Looks like your answer is YES. Same K rating and cross referenced equivalent from different manufacturers might have a different color. Thank you.

  6. #6
    Join Date
    Mar 2003
    Location
    New York
    Posts
    1,488
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Like anything lowest bidder for the oem, thickness of phosphor, amount of mercury, voltage, the +/- of each part; it all falls within tolerance. Just look at a torque wrench +/-.

  7. #7
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    38,905
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by DrSnowman View Post
    I asked about 2' and 4' T* fluorescent bulbs not LED's. Thanks anyway.
    I think gar's answer is just as applicable to LED's that are intended to produce a "white light" as they also use phosphors to try to do about the same thing as fluorescent tubes are doing.

  8. #8
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    19,864
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)


    Basically, whenever the spectrum of a light source does not match a perfect black body radiation profile of amplitude versus frequency assigning a single Kelvin Coordinated Color Temperature (CCT) number must be done using a specific definition (formula) that integrates the full amplitude spectrum to get a number.
    As a result, there are an infinite number of different spectra that produce the same number, but the impression of color to a viewer can differ greatly between any two.

    With incandescent lights the same question did not come up to nearly the same degree [sic] because except as modified by various types of filter glass and coatings, the spectrum of a hot filament follows a black body curve and so two lamps of the same CCT should give an identical color impression.

  9. #9
    Join Date
    Jul 2017
    Location
    Pennsylvania USA
    Posts
    12
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Appreciate all the input but I asked a very simple question...Do the colors of different brands of the same K rating fluorescent lamps match perfectly or are they slightly different? Almost all of the light fixtures in our buildings are Sylvania. The boss has been ordering GE equivalents because he can get them cheaper. But the colors don't appear to match all the time. I was hoping to get some of you to say yes or no so I could show him this thread and prove that there is a difference. I want him to order Sylvania.

  10. #10
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,251
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    180224-1712 EST

    DrSnowman:

    The answer is the colors are unlikely to be exactly the same. So a reasonable answer is no. But you should have understood that from what I and others told you. Further you need to do some study and experiments to understand the problem. I gave you various links to look at.

    I really suggest that you buy one of the inexpensive spectrometers and experiment. I think I would try the
    https://www.amazon.com/EISCO-Resolut...re-bullets-btf

    .

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •