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Thread: What colour temperature is subjectively closest to "pure white"?

  1. #31

    Default Re: What colour temperature is subjectively closest to "pure white"?

    They are about half black body radiation, half a blend of red, green and blue spectral lines that get smeared because of the high pressure/temperature.

    I haven't seen CRI measurements, but the only time someone makes a fuss about lighting selection is when some pigments are UV active. Thats from people who complain if you use incans of different age in one lighting setup.

  2. #32
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    Default Re: What colour temperature is subjectively closest to "pure white"?

    The problem with this question is each person has a different expectation about what "true white" should be. So the first consensus about it is that there is no universal "true white", neither from an objective of subjective viewpoint.

    Color perception varies from person to person, although fortunately it follows some universal paths. But the main complication is color is a multi dimensional concept. Should be "true white" about hue? In this case, a pure white should fall on the planckian locus or very close to it, say no more than 3 step McAdam ellipse and preferably, for definition, into a 1 step one (Duv<0,0007) so no any hue ("tint") is noticeable. I think in this point most people agrees. And between 3500 and 7000K.

    But color has many more dimensions, and agreeing which of them is more important is way more subjective. It depends of personal preference and somewhat on the culture you have grown in. Should "true white" render colors as more similar as possible as sunlight? If so, what sunlight phase? Morning, noon, afternoon? Cloudy or clear sky? In general, most consensus along the color scientific community has been to choose sunlight like light sources, the most prominent the Illuminant D65, in which is based CIELAB, the main official (CIE) color space. But many people feels 6507K as too "cold".

    It seems most people favor other dimension of color and light: its effect on our mood. Almost perfect white sources, as D65, but with a high percentage of blue white may be perfect for many people on a working space or when they want a feeling of cleanliness, but too "active" for a living room, where people prefer warmer tones so they feel more relaxed.

    Another dimension of lighting is the level of light itself. This parameter is often overlooked, but it is very important. A same color of light has different effect on our mood and render colors differently as luminance level varies. Although our brain usually compensates for changes and contrast when luminance varies, it is not the same a D50 at 5 cd/m2 than at 100 cd/m2. Actually, I think many people that identifies incandescent lamps as the most pleasant white would be surprised if tries a colder tone, as 4500K but at lower luminance.

    Should "true white" be pleasant or reliable on color rendering? I think the point most difficult to reach a consensus is this. Should it make scenes appear "natural" (whatever it means) or vivid, with enhanced color?

    In my personal preference, I think a true white is somewhere between 4000 and 5000K, very close to planckian locus and providing a luminance matched to each application.

  3. #33
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    Default Re: What colour temperature is subjectively closest to "pure white"?

    Reviving a sleepy thread. . . this caught my interest as I spend 8-10 hours a day in an office lit by 3 lamps. Initially I just put the reg. bulbs in there that were "full spectrum" 40 or 60 watt. The result was flickering . . . I work in a big office buliding so checking for the power flow to the outlets is out. So, I then tried those low watt cfl bulbs that were rated "warm". The flickering was much better , but still there. I'm VERY aware of such flickerings, a sad thing for sure! Finally I have in there two LED bulbs that use 6 watts or something like that. I'm at home now, so I cannot confim what temp the bulbs are , but I know they are warm. My goal in my office was to create warm ambiance. . . and soft lighting. I did accomplish the soft lighting part, but after reading this thread, I think I've gone overboard on the warmth scale. And, I do get headaches nearly everyday at work (I thought it was due to the nature of my work). And, I find that at certain times it seems as though the room is "foggy". I know that probably doesn't make sense, but that is how it seems by the end of the day and when my eyes and ears are REALLY tired. So I think I will get some bulbs today that are in the 4500 - 5500 range and see what diff. that makes. This has been an expensive experiment. And, considering the LED are the way I must go for less flickering, it will be even more expensive after the new bulb purchase. If anyone has any thoughts on my approach, I'd love to hear them. And, thanks for this most informative thread!
    "I always prefer to believe the best of everybody it saves so much time." - Rudyard Kipling

  4. #34
    *Flashaholic* fyrstormer's Avatar
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    Default Re: What colour temperature is subjectively closest to "pure white"?

    Use a halogen desk lamp. The rest of the office can be lit by flickery fluorescent bulbs and it won't matter as long as the light near your workspace is steady.

  5. #35
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    Default Re: What colour temperature is subjectively closest to "pure white"?

    good info to have . . . thanks fyrstormer!
    "I always prefer to believe the best of everybody it saves so much time." - Rudyard Kipling

  6. #36
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    Default Re: What colour temperature is subjectively "pure white"?

    Quote Originally Posted by ElectronGuru View Post
    My testing shows 4300K to be the mark, but 4200-4600 is close enough in most applications. 5000K is still pretty blue. 3000K is quite yellow.

    One of the issues is that this scale is designed from the use of a single technology (glowing hot metal). So a non-glowing-metal source (LEDs for example) can be (measure at exactly) 4300K and still be tinted with a color not on the color temp scale, like green.
    I agree with you because the question in the thread's title says: "subjectively".

    And by the other hand we must to remember that "daylight" in really fact means a narrow but variety range of tone colors: at the morning tends a bit to blue; and in the evenings turns a bit to the yellow.

    But the word is: "pure white" I am waiting for the arrival of some cfl's; then I will test for myself; some facts about some labels in the lamps.

  7. #37

    Default Re: What colour temperature is subjectively "pure white"?

    What really confuses me is that the 4100K T8 fluorescents in my home closets are nice and white, (but I would say too cool for living spaces). But my Zebralight neutrals 4200K and 4400K lights are completely different. If my closet lights are really 4100K, the zebralights have to be below 3000K. I couldn't imagine the tolerance to be so high.

    My Fenix PD32UE torches are also very close to pure white, I'm guessing 5000K. But still a little bluish.

    L10s w/ Nichia 219, PURE white (high CRI or not)
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  8. #38

    Default Re: What colour temperature is subjectively "pure white"?

    Quote Originally Posted by markr6 View Post
    What really confuses me is that the 4100K T8 fluorescents...
    The problem is the scale itself. Color temp is linear, 1 dimension like a long thin road. Designed to measure incan sources, its like stating your location in a small town based solely on how far along a central railroad track you are standing.

    Modern light sources are 2 dimensional, having multiple colors and other variations. A given LED or fluorescent light source can be so far away from that center, as to be meaningless. They K value is simply how close you can get to actual, on that railroad track. Distance from the track is completely ignored.

  9. #39

    Default Re: What colour temperature is subjectively "pure white"?

    Quote Originally Posted by ElectronGuru View Post
    The problem is the scale itself. Color temp is linear, 1 dimension like a long thin road. Designed to measure incan sources, its like stating your location in a small town based solely on how far along a central railroad track you are standing.

    Modern light sources are 2 dimensional, having multiple colors and other variations. A given LED or fluorescent light source can be so far away from that center, as to be meaningless. They K value is simply how close you can get to actual, on that railroad track. Distance from the track is completely ignored.
    Got it...thanks!
    GOOD TINT!

  10. #40
    *Flashaholic* fyrstormer's Avatar
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    Default Re: What colour temperature is subjectively "pure white"?

    The distance away from the actual blackbody radiation line-graph isn't ignored, it's expressed as Color Rendering Index. 100% CRI means the light contains the exact radiation spectrum indicated by the color-temperature it is associated with. I don't know if 0% CRI exists, but I suppose it would mean the light has the same tint as the color-temperature it's associated with, but it's all the way at the edge of the visible-color gamut, far away from the blackbody radiation line-graph.

    One example would be cyan light, which is a single color, but it *could* be labeled as 40000K with 0% CRI -- at a casual glance the overall tint of the light source might look the same, but the cyan light would be completely incapable of rendering any colors except cyan, unlike true 40000K light, which can render all visible colors, albeit with a strong bluish tint.

    On the other hand, a deep red light would also be single-color, but could be labeled as 1000K with 100% CRI. That's because the dimmest blackbody radiation that people can see only consists of a narrow range of deep red light, mixed with a bunch of infra-red that we can't see, so a single-color deep red light would have the same rendering capability as true 1000K light.

    If there's a problem with using blackbody radiation to rate the quality of light, it's mostly that people don't actually know what makes good light anyway, so they use hot glowing things as a benchmark, because they can instinctively relate to it.
    Last edited by fyrstormer; 02-26-2014 at 11:44 PM.

  11. #41

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    Default Re: What colour temperature is subjectively "pure white"?

    Subjectively, I much prefer cooler tints. Anything below 5000k looks off to me...a white sheet of paper doesn't look white any more, it is that simple. I don't care how it "feels", I just want white to look white. As phrased, it is a silly question (though it has generated some interesting comments), because to know what the subjective "pure white" color is, all you have to do is some testing on your own. No one else can tell you what your preference will be, or what color temperature you will perceive as "pure white". For me, 5500-6500k is ideal. I originally bought into the idea that it wasn't good for home lighting, but after buying several different color bulbs, and trying them out, I have changed my mind. My ideal setup is similar to how saabluster designed the Rev Captor...a couple bright 6500k bulbs, and one dimmer 3700k bulb to boost the CRI.

  12. #42

    Default Re: What colour temperature is subjectively closest to "pure white"?

    There is no "color" label that is actually meaningful other than as a range.

    What we CALL red, or blue or green, etc, is simply a concept, not an exact value.

    For example, real colors are actually infinitely varied, and the wavelength rather than the "temperature" would be a more accurate way to describe what we CALL "color".

    There are a range of wavelengths that we might consider to be be "red" for example. Which is the "real red"?

    They ALL are, but, based upon our societal influences, each of us will CONSIDER a particular wavelength RANGE to be "the most red", etc.


    For example, we might look at a color, and describe it as sort of a yellowish green. Why do we not have a NAME for that color, the way we have for yellow, or green? Its because we just happened to name only a few colors, and could have just as easily labelled yellowish green as yellow, or green, or blue, or ishcabible, etc.

    In Greek times for example, violet was how they described some people's hair, as they had fewer names for colors, so, black hair was called violet. This makes sense, as when you look at a color chart, violet DOES tail off to what we might call black....but they didn't have black as a color label yet...it was violet. IE: Black was violet. If we asked "what's the "true violet", what would they have said? The color of a Greek maiden's hair?







    We have arbitrarily labeled part of the spectrum as being "a color". We even talk about "how many colors" are in a rainbow, etc. ALL the colors are in a rainbow, but, we artificially made up "break points" that divide the infinite number of colors into groups.

    These groups do not actually exist in any physical sense of the word, other than by human consensus...and, different groups of humans have broken them down differently, so there are "colors" that people from different regions, etc, can argue about.....but, its all about the labels they each ascribed to parts of the spectrum.

    To FURTHER attempt to use a color TEMPERATURE scale to describe a COLOR is going to be even more vague, as its not really about color as much as about the color at a particular time of the day for instance.


    IE: There is no "color temperature" that = "pure white".

    Last edited by TEEJ; 08-29-2014 at 05:52 AM.

  13. #43

    Default Re: What colour temperature is subjectively "pure white"?

    I like the displays at home depot. I think they use CFLs which I don't use, but still gives you a good general idea.


    GOOD TINT!

  14. #44
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    Default Re: What colour temperature is subjectively closest to "pure white"?

    Quote Originally Posted by Twinbee View Post
    Yes, but that's just the sensory contrast of going from one situation to another. If you stick in one enviroment, then there should be a colour temperature that's closest to what most people would consider pure white (as you imply yourself afterwards).
    Millennia of experience deny a constant environment. Sunlight ranges from 3000 to 7000K CCT, depending on conditions (Sunset, overcast, noonday, etc). You're looking for something that's not possible.

    Look for a light source between 3000K and 5000K (Higher CCT for work-like tasks, lower for relaxing tasks), with good color perception card results. R9 is a weak point for LEDs and arc lamps - It's a delicious red. The blues are weak for hot filaments.
    My biggest light-hog is my camera.

  15. #45

    Default Re: What colour temperature is subjectively closest to "pure white"?

    Lots of conjecture on this thread but the LRC did a study and found within the study group that almost without exception people picked 4000k as white +/- a few hundred k after adaptation.

  16. #46

    Default Re: What colour temperature is subjectively closest to "pure white"?

    I did my own study and found it to be 4300, within the range above:

    http://www.candlepowerforums.com/vb/...olor-Reference

  17. #47
    *Flashaholic* fyrstormer's Avatar
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    Default Re: What colour temperature is subjectively closest to "pure white"?

    4300K is significantly warmer than pure white to my eyes. 6000K is pure white to me, but I prefer 5000K because I like just a teensy bit more yellow in my light.

  18. #48

    Default Re: What colour temperature is subjectively closest to "pure white"?

    Quote Originally Posted by fyrstormer View Post
    4300K is significantly warmer than pure white to my eyes. 6000K is pure white to me, but I prefer 5000K because I like just a teensy bit more yellow in my light.
    That's my preference as well. I don't enjoy brownish yellow light. Some people clearly do. Ideally you want a complete spectrum but led's cannot do that as I understand it. One thing I know. I find greenish light intolerable but I'm told some hunters prefer it.

  19. #49

    Default Re: What colour temperature is subjectively closest to "pure white"?

    The study was not about preference but about what light when dark adapted looked most "white".

    In terms of preference under the black body ... Was the preferred color point at all CCTs in another study.

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