# "Neutral" vs Cool light



## hk dave (Jan 17, 2010)

Hi everyone. I have a question about something that has confused me about the flashlight world.

I've noticed a lot of posts where people refer to "Neutral" light and talk about it's warmness and that it is more close to the color of the sun.

That is a bit confusing to me since the suns light is actually very cool in comparison to standard tungsten light bulbs.

Sunlight mid day runs at 5500 Kelvin... Incandescent runs roughly 2800 to 3200 kelvin. 

So when people refer to "neutral" light... such as the quark mini neutral... are they saying it is WARMER or cooler then the standard quark mini neutral?

I'm confused as to the terminology used in the flashlight world, please excuse me 

Thanks! 

(On a side note, I believe it is a generally accepted idea that sunlight is considered neutral and that incandescent is considered warm and far from neutral. So if it is the case that the flashlight world believes that the yellowish light from incandescent light bulbs is neutral, i wonder how that came to be? Like when and why was it decided that "neutral" would be the warmer light? )


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## richardcpf (Jan 17, 2010)

hk dave said:


> So when people refer to "neutral" light... such as the quark mini neutral... are they saying it is WARMER or cooler then the standard quark mini neutral?


 
You really confused me there... when they say neutral quark mini, they mean it will output a warmer light than the normal or cool tint quark.

But to make it simple neutral is more like a mix between sunlight and incan, and cool is white or maybe a bit to the blue side. Dont expect neutral to produce incan light color, its just sightly warmer than white.


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## PeaceOfMind (Jan 17, 2010)

Well, I'm not an expert by any means, but I believe that:

-"Cool white" LEDs are generally quite a bit cooler than the sun. A lot of this is because "white" LEDs are, at heart, blue LEDs + phosphor and so have a very strong blue component

-"Neutral white" LEDs that most people here talk about are quite a bit warmer than the cool white LEDs. I believe they tend to be a bit warmer than the sun as well, but not by too much. They are generally cooler than incan lamps.


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## hoongern (Jan 18, 2010)

I think everyone has their own definition of warm/neutral/cool, but for me, I place the sun (~5500-6000K, debatable) to be neutral, and anything less than that is warm, while anything more is cool.

But that's my own definition. But it's easy for me to explain to others - I say - "The sun is neutral. Anything yellower is warm, anything bluer is cool". Basically that.

But I respect other's definitions - I generally try to specify exactly temperatures as then one doesn't need to worry about what "Neutral", "cool" or "warm" means - since they have the exact color i.e. "4500K". Unfortunately most manufacturers won't specify this information.


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## Egsise (Jan 18, 2010)

Human eye adapts to the light which is available so I wouldn't worry about it that much.

Problems begin when you have lights with different tints....

Camera white balance is set to daylight, lumen readings are guessimates:

Fenix LD10 100lm.......47 Quark AAw 14500 150lm...Fenix TK20 150lm..............MG PLI warm white 300lm


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## hk dave (Jan 18, 2010)

How interesting indeed. Thanks for your answers. In the flashlight... neutral means "warm". Got it! PHEW almost bought the wrong light.


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## Curious_character (Jan 18, 2010)

If we look at a flat black object in a completely dark room with the proper equipment, we see that it radiates light at invisible (infrared) wavelengths. This is the basis for thermal imaging equipment. The spectrum of this emitted "light" is broad, centered in the infrared region. Since all black bodies radiate the same spectrum, it can be simply described by a single number -- the "color temperature". By convention, this is in Celsius degrees above absolute zero, or degrees Kelvin. (Zero Celsius is about 273 Kelvin.) So the spectrum of a room temperature (about 25 degrees C) black body is about 300 Kelvin.

Get it hotter, and the wavelength of the spectrum gets shorter, until it reaches the red end of the visible spectrum -- literally "red hot". This happens at about 800 Kelvin (about 500 Celsius, or 900 Fahrenheit). As it gets hotter yet, the wavelength keeps getting shorter, making the overall color shift toward blue. Remember, the spectrum is wide and includes a range of colors, so you'll never see "green heat", for example. Over the visible spectrum, the hotter the body gets, the bluer the light it produces. Incandescent lights run at about 2800 Kelvin, and that's their color temperature. Daylight is on the order of 6500 Kelvin, and it's the spectrum you'd get by heating a wire or other object to that temperature.

The spectra put out by LEDs and fluorescent lights are different than simple hot black body radiation -- they have peaks, dips, and holes, or even just a few discrete lines rather than a smooth, broad spectrum -- , so declaring a single color temperature doesn't tell us everything about the spectrum like it does for an incandescent light. Yet the number is used and it does tell us generally how the overall color looks to us.

A very confusing factor is that popular parlance describes a reddish light as "warm" -- after all, fire is warm, and it's red -- and a bluish light as "cool" -- ice is blue, isn't it? But like I just described, you actually have to heat something hotter to get that "cool" blue light than to get "warm" red light. So we're stuck with having high color temperature lights popularly described as "cool" and low color temperature lights as "warm", even though the actuality is exactly the opposite.

Of course, there are other ways of making light than heating things up. A fluorescent tube generates invisible but high energy UV light with an electrical discharge, and uses it to excite a phosphor that emits visible light. LEDs use solid state physical phenomena to generate light directly. White LEDs are currently made by coating a blue emitting LED with phosphor. And fireflies and those sticks you buy at the dollar store generate light chemically with virtually no heat at all. So the actual physical temperature of the emitter doesn't have to have anything at all to do with the color and hence the color temperature.

Color is a very complex topic, and color temperature and CRI are woefully inadequate to describe complex spectra like LEDs put out, but hey, when has that ever stopped anyone? There's a lot more information on the web for anybody who's interested in the topic. Googling "color temperature" or "light spectrum" will get you started.

c_c


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## Egsise (Jan 18, 2010)

hk dave said:


> How interesting indeed. Thanks for your answers. In the flashlight... neutral means "warm". Got it! PHEW almost bought the wrong light.


Umm, neutral means neutral. 
LD10 Q5 is cool, QAA Q3 5A and TK20 Q2 5A are neutral, MG PLI MC-E 7B or 7C is warm.


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## T0RN4D0 (Jan 18, 2010)

I would say that it goes something like this, but different manufacturers and sources set different boundries. 

I found one that goes like this...

3,600K~4,000K -warm white
5,000K~6,500K -neutral white
7,000K~10,000K -cool white

And on wiki a page about fluro tube says that 4.1K is allready cool white. So this things are different and it looks like no serious standards apply. 

My idea of led color temps would be something like this;

*under 4K warm 
4-5K neutral 
over 5K cool *



So the yellow LEDs you (rarely) see are usually warm whites, and are there for the incan nostalgics 

The white leds are the white ones, good color rendering, a lot of flashlights with those installed.

Then we have the cool whites, with blueish accents, typically all the cheap flashlights have those. They apear bright, but aren't that good at actually illuminating things, especially outside where white color is poorly represented. 

Also, not that there are only 3 basic divisions, and most of the "neutral" LEDs are usually 4000k, warm 3k, and cool 5k. But you can get freaking alien blue LEDs, which are still cool. Also neutral are sometimes marked 5k and so on. Basically you're playing a lottery when buying online without any color temps stated.


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## hk dave (Jan 18, 2010)

Egsise said:


> Umm, neutral means neutral.
> LD10 Q5 is cool, QAA Q3 5A and TK20 Q2 5A are neutral, MG PLI MC-E 7B or 7C is warm.



So when talking about the Quark Minis... when they say neutral they mean 5500K?


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## Quension (Jan 18, 2010)

hk dave said:


> So when talking about the Quark Minis... when they say neutral they mean 5500K?



The neutral white Quark MiNis use tint 5A3, which Cree puts at 4000K.


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## Curious_character (Jan 18, 2010)

"Neutral" means just about anything the manufacturer wants.

I just fitted out an addition with Cree LR6C recessed lights. They're 3500K and marked "neutral white". Their "warm white" is 2700K and mimics incandescent light very well.

c_c


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## dirtech (Jan 18, 2010)

Curious_character said:


> If we look at a flat black object in a completely dark room with the proper equipment, we see that it radiates light at invisible (infrared) wavelengths. This is the basis for thermal imaging equipment. The spectrum of this emitted "light" is broad, centered in the infrared region. Since all black bodies radiate the same spectrum, it can be simply described by a single number -- the "color temperature". By convention, this is in Celsius degrees above absolute zero, or degrees Kelvin. (Zero Celsius is about 273 Kelvin.) So the spectrum of a room temperature (about 25 degrees C) black body is about 300 Kelvin.
> 
> c_c



Thanks for that explanation. I always wondered what people were talking about when they referred to "black body".


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## Curious_character (Jan 18, 2010)

dirtech said:


> Thanks for that explanation. I always wondered what people were talking about when they referred to "black body".


Technically, a "black body" is an object that absorbs all the electromagnetic energy hitting it, and reflects none. When dealing with light, it only has to be "black", that is, completely absorptive, over the light part of the electromagnetic spectrum. An object that fits this definition over the visible light spectrum looks flat black to our eyes. A black body is also the most perfect radiator, radiating all wavelengths equally well, which is why it's used for this definition. There's a lot more detailed information on the web, like in this Wikipedia article: http://en.wikipedia.org/wiki/Black_body.

c_c


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## hoongern (Jan 18, 2010)

T0RN4D0 said:


> Then we have the cool whites, with blueish accents, typically all the cheap flashlights have those. They apear bright, but aren't that good at actually illuminating things, especially outside where white color is poorly represented.



Let's remember that this is very much down to personal preference. We're talking about tints here, not CRI, which is a different matter completely.

*From Cree's datasheet:*
Typical CRI for Cool White & Neutral White (3,700 K – 10,000 K CCT) is 75.
Typical CRI for Warm White (2,600 K – 3,700 K CCT) is 80.

So between 3700-10000K, it's all just tint preference, since they have the same CRI (Of course, talking about Crees here, maybe some other high-CRI leds [or low CRI] would be different)

Not saying you're right or wrong. (For the record, I like incans outdoors, because of their 100CRI, not their tint, and I don't like blue tints) 

But it's a preference.


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## Curious_character (Jan 18, 2010)

The quoted figures are just for the phosphors chosen for Cree LEDs. CRI depends on the nature of the phosphor, but it can also be misleading. Under 5000 Kelvin, CRI just tells you how closely the light imitates a black body at the same color temperature. Incandescent lights running at 2500 and 5000 kelvin (if you could get one that hot) both have a CRI of 100. But things sure will look different when you shine one light at them then they do under the other light. And sunlight would make things look different yet. And everything would look very red under a light with 1000 degree color temperature and CRI of 100.

There are a number of ways to get different color temperatures, and different CRIs, from LEDs. Cree's LR6 and LR6C recessed lights, for example, have color temperatures of 2700 and 3500 degrees respectively, and both have a CRI of 90. This means that the LR6 does a good job of imitating a 2700 degree incandescent and the LR6C a good job of imitating an incandescent light or black body heated to 3500 degrees. They don't look the same, and they don't render colors the same. The relatively high CRI in this case is achieved by using a combination of red and white LEDs, and using a color sensing and feedback system to automatically keep the color constant as the LEDs age differently. Other phosphors can be used, too, but apparently ones with high CRI tend to be less efficient, at least among currently known phosphors. You can be sure there's a major effort to develop better phosphors!

c_c


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## hoongern (Jan 18, 2010)

Curious_character said:


> The quoted figures are just for the phosphors chosen for Cree LEDs. CRI depends on the nature of the phosphor, but it can also be misleading. Under 5000 Kelvin, CRI just tells you how closely the light imitates a black body at the same color temperature. Incandescent lights running at 2500 and 5000 kelvin (if you could get one that hot) both have a CRI of 100. But things sure will look different when you shine one light at them then they do under the other light. And sunlight would make things look different yet. And everything would look very red under a light with 1000 degree color temperature and CRI of 100.
> 
> There are a number of ways to get different color temperatures, and different CRIs, from LEDs. Cree's LR6 and LR6C recessed lights, for example, have color temperatures of 2700 and 3500 degrees respectively, and both have a CRI of 90. This means that the LR6 does a good job of imitating a 2700 degree incandescent and the LR6C a good job of imitating an incandescent light or black body heated to 3500 degrees. They don't look the same, and they don't render colors the same. The relatively high CRI in this case is achieved by using a combination of red and white LEDs, and using a color sensing and feedback system to automatically keep the color constant as the LEDs age differently. Other phosphors can be used, too, but apparently ones with high CRI tend to be less efficient, at least among currently known phosphors. You can be sure there's a major effort to develop better phosphors!
> 
> c_c



Yup, I probably should have made it clearer that those figures were just for Cree's 7090 LEDs (XR-E, XP-E, XP-G). Indeed there are other High CRI LEDs at various CCTs. 

However I quote Cree because a high percentage of flashlights we use are Cree-based. 

*7090 XR-E *(http://www.cree.com/products/pdf/XLamp7090XR-E.pdf)*:*
Typical CRI for Cool White & Neutral White (3,700 K – 10,000 K CCT) is 75.
Typical CRI for Warm White (2,600 K – 3,700 K CCT) is 80.

*XP-E* (http://www.cree.com/products/pdf/XLampXP-E.pdf):
Typical CRI for Cool White & Neutral White (3,700 K – 10,000 K CCT) is 75.
Typical CRI for Outdoor White (4,000 K - 5,300 K CCT) is 70.
Typical CRI for Warm White (2,600 K – 3,700 K CCT) is 80.
*
MC-E* (http://www.cree.com/products/pdf/XLampMC-E.pdf):
Typical CRI for cool white and neutral white (3,700 K - 10,000 K CCT) is 75.
Typical CRI for warm white (2,600 K - 3,700 K CCT) and EasyWhite is 80.

*XP-G *(http://www.cree.com/products/pdf/XLampXP-G.pdf)*:*
Typical CRI for Cool White (5000 K – 8300 K) is 75.

Honestly, I actually prefer cool-neutrals, but it's for their *TINT* which is a personal preference. Not their *CRI*. I just feel that there's a lot of confusion and misinformation that people think the neutrals have better CRIs than the cool whites. They generally have the same CRI (with XP-E/XR-E/XP-G that is). _In fact_, you can see above that the Outdoor White XP-Es (4000-5300K) has a lower CRI. So Tint and CRI are not _always_ directly proportional. Although warmer tints _generally _are higher CRI - but as noted above, not always!

Please correct me if I'm wrong! I do make mistakes...


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## Yoda4561 (Jan 19, 2010)

The 5A tint is right around 4300K, according to my camera's white balance. It sits firmly between a good incan and the more common cool white LEDs, to me it's almost the perfect neutral white color, though it is a touch pinkish when compared to daylight. Judged on its own merit at night, away from other light sources it appears a perfect white color, with excellent feedback on yellow/red/brown/green colors. 

Edit: As I understand CRI it's pretty irrelevant outside of the professional image design and printing community. Basically it just tells you how close the spectrum of your light source compares with a glowing tungsten filament at a similar color temperature, not necessarily how well the light works to see things, which neutral whites excel at IMO. I'll take my 75 CRI 5A emitter any day over a 100CRI incan lamp, the incans are too yellow for me, and that yellow can wash out certain colors almost as badly as the blue tinted lights can. Some folks think cool whites are great, and maybe they are depending on the environment you're in and your own color vision, which varies widely from person to person.


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## Curious_character (Jan 19, 2010)

hoongern said:


> . . .Honestly, I actually prefer cool-neutrals, but it's for their *TINT* which is a personal preference. Not their *CRI*. I just feel that there's a lot of confusion and misinformation that people think the neutrals have better CRIs than the cool whites. They generally have the same CRI (with XP-E/XR-E/XP-G that is). _In fact_, you can see above that the Outdoor White XP-Es (4000-5300K) has a lower CRI. So Tint and CRI are not _always_ directly proportional. Although warmer tints _generally _are higher CRI - but as noted above, not always!
> 
> Please correct me if I'm wrong! I do make mistakes...


That's right. I think one of the main differences between today's "cool" and "warm" or "neutral" white LED is that the "cool" one tends to have a bigger spike in the blue end of the spectrum. This seems to help efficiency since it probably just means that more of the original blue LED light is getting through. But it's detrimental to the CRI. This will change as the technology progresses and new phosphors and techniques are developed.

This is a fascinating time to be involved with LEDs. The technology has advanced so far in such a short time, but it's just beginning. We ain't seen nothin' yet!

c_c


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## hoongern (Jan 19, 2010)

Curious_character said:


> That's right. I think one of the main differences between today's "cool" and "warm" or "neutral" white LED is that the "cool" one tends to have a bigger spike in the blue end of the spectrum. ...(skipped)... But it's detrimental to the CRI.
> 
> c_c



If you look at the graphs on page 5 of the XR-E datasheet:

Both cools and neutrals have exactly the same intensity blue spike (probably due to using the same phosphors), hence [if we are to conclude that those blue spikes are the cause of detrimental CRI] they both (Neutral included) have 75 CRI. As such, Neutral does not actually improve CRI over cools. Just a 'warmer' tint which is preferable to some. So it all boils down to tint preference again, of which to me all sides are perfectly acceptable. (I just don't want people to think that the Xlamp neutrals have better CRI than the cool ones --> If you buy neutrals, buy it for the tint!)

However, the warm ones have a smaller blue spike, leading to their higher 80 CRI. Possibly because of different phosphors used for the warm ones.


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## ImGeo (Jan 19, 2010)

Very thoughtful and informational (and thought provoking) thread. Very much like it!

Overalll, through personal testing, I prefer the Neutral (~4300K) LED's, indoor and out. Though some find the neutral tint ugly, I find it much more practical in color rendition (much better matches the lighting I'm used to (CFL bulbs), and overall produces better rendition of yellows and reds). This better color rendition of yellows and reds comes as a huge advantage outdoors, and for me and others, provides better depth perception and color rendition.

However, I recently chose a R5 cool white Quark Mini over the Neutral Q3 5A due to the brightness (Neutral is currently about 30% less bright in terms of lumens). The cool white I have is not actually a pure whiteish light, but has a tint of greenish. Not exactly the best tint I like, but LED's are a lottery.

Being a Mini, I expect to use it around the house, or occasionally outdoors. However, when I get a primary outdoor light (which will probably be a larger and hand-sized light), it will preferably be Neutral (although the sacrifice of lumens is a big consideration)


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## Curious_character (Jan 19, 2010)

You'd be very hard pressed to detect a 30% change in brightness. And in terms of throw, the brighter light would light an object at 114 feet at the same brightness as the dimmer one would at 100 feet -- just a 14% improvement. A further complication is that lumens are measured in a way that weights the spectral components according to our eye's daylight sensitivity, which is quite different from its spectral sensitivity at night, so a light with a lower lumen output can actually be brighter than one of a different spectral content but higher output, when viewed with night-adapted eyes. (Realistically, though, I think this would be significant only with very dim lights.) But the bottom line is that a lumen specification can be quite misleading when comparing lights with different colors and/or spectral content. It's really necessary to evaluate lights subjectively under actual use conditions rather than to make decisions based on lumen (or for that matter, color temperature or CRI) specifications.

c_c


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## Woods Walker (Jan 24, 2010)

Curious_character said:


> It's really necessary to evaluate lights subjectively under actual use conditions rather than to make decisions based on lumen (or for that matter, color temperature or CRI) specifications.
> 
> c_c


 
Yup. I often hike on blue blaze trails and sometimes these trips turn into night hikes. This is a blue blaze.







Sometimes these are not perfect.






Looks like something that would be hard to miss with any LED flashlight/headlamp but that isn't the problem. This is tree lichen from the same trail/hike.











With some cool tinted LEDs this stuff looks 100% the same as the trail markers at night. Heck looks very near in the sun too. Still with a neutral/warm/whatever LED I can pick out the real trail marker much faster. So will take a few less lumens for a tint that will not be too cool.


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## Benson (Jan 24, 2010)

Yoda4561 said:


> Edit: As I understand CRI it's pretty irrelevant outside of the professional image design and printing community. Basically it just tells you how close the spectrum of your light source compares with a glowing tungsten filament at a similar color temperature, not necessarily how well the light works to see things, which neutral whites excel at IMO.



Yes, that's what CRI measures directly, but it's sometimes relevant not because we're in love with hot tungsten, but because it's a reasonably good proxy for how "full" the spectrum is.

Consider:
It's possible to make white of any desired temperature from two arbitrarily narrow-band sources (e.g. lasers), but this will cause an effect analogous to color-blindness, essentially downgrading our tristimulus vision to bistimulus. It will have very low CRI, accurately reflecting its poor rendition of most colors.

A typical white LED has two spectral peaks, a blue one perhaps 50nm wide, and a broad yellow one -- much better color vision, although some colors will be washed out, and a CRI of 80 or so.

An overdriven halogen bulb will give a nice >3500K with a rather full spectrum, and being roughly neutral, will light objects very well -- perhaps a yellowish cast, but all colors are clearly distinguishable -- and give a correspondingly high CRI of 100.[/quote]

OTOH, while a "neutral" blackbody spectrum (4500K or so) will have a wide central peak, there's still some taper to both the red and violet ends, so paradoxically the most uniform spectrum (flat across all wavelengths) would be penalized in CRI. But not a big issue, since there are no light sources like that in common use...

Anyway, as for why the fullness matters, and therefore why CRI matters as the closest standardized measurement, I'll go to the resident authority on spectrally non-uniform pigments:


> _Me:_ _[Explains how I replaced 5x 40W globe bulbs over my bathroom sink with 3x 14W 4300K CFLs for brighter and whiter light at a quarter the heat generation]_
> _Sister:_ But you _can't_ do makeup under fluorescents -- although I guess that doesn't bother you!
> _Me:_ *. . .*
> 
> _Me:_


I thought about asking for recommendations of cosmetics that were known to have particularly non-true color under fluorescents in hopes of making my own pseudo-CRI test kit, but decided not too. She thinks I'm weird enough already. The point is, there are some things where color will be off, and they're not all in design fields. So if I were selecting a light to go spotting for most wildlife, I'd go for lumens (or rather candelas), as long as the CCT is bearable, and neglect CRI altogether; if one were spotting for girls though, maybe CRI would trump CCT... 

(Tangent: Wouldn't there be a market for cosmetics designed to appear natural under typical fluorescent lighting? If I was a cosmetic manufacturer, I'd look into it...)


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## hk dave (Jan 24, 2010)

I was under the impression that the scientific community specifies "neutral" at the color of the sun during mid day... which is roughly 5500K.

So wouldn't 4300 make it rather warm?

Hehe it's why i said, "Oh so when manufacturers say 'neutral' they really mean 'warm'?"

Sorry guys, a decade of being a photographic color printer and a photoshop retoucher have made me sooooo sensitive to color that 4300K feels to me to be as yellow as a lemon.... i can't even be in a room with regular incandescents... i get dizzy.

I'm broken.


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## Zeruel (Jan 24, 2010)

DHart said:


>



From DHart's beamshots, I gather M60 (looks warmer in real life) and LF2XT (Q4) are neutral where others like L-Mini (Q3) & Jet-III M (Q3) are warm. The "blue" ones are, of course, cool.


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## Curious_character (Jan 26, 2010)

I just got my hands on a few high-CRI SSC emitters (S42180 -- 4000K, 93 CRI) and put a couple into flashlights. I took one of them on a walk along with a light having a more common cool white LED of about the same output level, and with both on, rapidly lit up various scenes with each one in turn. The most striking difference was that grass, moss, and dirt all looked very nearly the same color -- green -- under the cool white LED, but the brown dirt was very distinct under the hight CRI light. No surprise, since the high CRI emitter puts out proportionally more red. I suspect this is at least one reason people report that warmer lights give more of a 3D sensation -- with leaves and branches, and grass and dirt, being about the same color with the cool LED, you do lose some depth clues. Interesting.

c_c


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## Egsise (Jan 26, 2010)

Muddy trail with tree roots, I've heard of the neutrals are better but haven't tested this.

If a hunter is searching a wounded or dead deer/moose etc I assume that neutrals are better.
Does anyone have any comparison shots about this kind of thing, I would take those but 2 ft of snow in here....


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## carrot (Jan 26, 2010)

I think the "neutral white" nomenclature is terribly misleading. It is a warm white, vs. the usual cool white. 

While there is only one true white (#FFFFFF), in our world there are many shades of white. Neutral suggests that it is somewhere in between warm and cool but in fact it is much more on the warm side.


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## Egsise (Jan 26, 2010)

I guess it depends on what you compare it.
Q3 5A and Q2 5A looked warm before I got my MC-E 7C....


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