Why are warm tints better than cool tints for colour rendition?

Why? and why is a warm tint preferred for outdoors?

Check out selfbuilt's new thread in the LED forum:
https://www.candlepowerforums.com/threads/227176
Whether you like them or not is up to you, but his comparison pics will help you see the difference.

I don't recall of the specifics but in general terms it has to do with differences in the spectrum of light. What we're used to during the day is "full spectrum" light from the sun. At night we're starting from a position of effectively no light and we're relying on our flashlights to emit not just light but also as much of the full spectrum as is practical to approximate what we're used to. As I understand it the warmer end of the spectrum, from yellow to red, are the first to diminish as light output falls. For instance you'll notice things look a lot cooler or more blue in the dawn and dusk than in the middle of the day. A warm spectrum light adds more of that back in so what you're viewing looks more like what you'd be used to seeing during the day. This is why optics meant for use under dusky conditions are often made with a yellow filter.

While things do look prettier in a warm tinted light to me I'd also say that in practice it doesn't actually allow me to see any more or any faster than a cooler tint. The illuminated scene does appear more "live." Brighter does make a more noticeable difference to me. Many have said that warm tinted light cuts through fog and smoke better than cool tinted light but I haven't had an opportunity to really test this out yet. Your eyes may vary.

comparison pics don't always do neutral LEDs justice. I recently modded my Akoray 106 to a neutral white, and it makes a big difference in the woods near my house. As an example, a rabbit at 20 yards was almost unseeble with my cool white L2Dce, but with the neutral Akoray, it showed up clearly. The L2Dce is actually much brighter than the Akoray.
Some yellow/gold flowers showed up as very pale yellow with the L2D, but vibrant yellow/gold with the Akoray.
Tree trunks and blackberry bush stems all showed up as kind of greyish and hard to focus on with the L2D, but the Akoray showed them as various shades of brown and green, and much easier to see details. My dog, under the L2D shows up as kinda beige, but with the Akoray, she shows up much closer to her actual orangy brown. (as a irrelevent side note, my dog loves my flashlight addiction, since we go for alot of night walks!)

All this was noticed just last night, when I took a walk with my dog around the neighborhood, park, and woods.

My L2D used to be my favorite light, but now its my Neutral modded Akoray! I am a convert!
I am getting the Fenix TK 20 soon!

On the other hand, some prefer cooler lights, and some just put brightness over everything. whatever floats your boat!

It never ceases to amaze me how super bright cool-white LEDs look so dark when you shine them on hedges/trees or brown mud. You get almost nothing coming back...

Neutral or (even better) warm white tints may not measure as bright when someone shines it into your eyes, but you get much more of it bouncing back of real world stuff, hence I find it is much better to see by.

I've been wondering about this myself. When I compare my LED to my incan, the led wins in brightness outside, after adjusting the level to equalize them indoors. But the incan shows more detail, while the LED makes appear muddy without depth. When purposely blinding myself, again equalized, the incan seems more disruptive to my nervous system. (I just noticed BillyNoMates has a different experience on that one) But the yellow is butt ugly when wall hunting.

I should probably go for a warm LED for my next light or mod. I just must resist the urge to white wall hunt. :sick2:

If you look at the spectral output of a cool white vs warm white emitter (let's say Q5 WC vs Q2 5A) The 5A warm tint is putting out MUCH more light between the green and red of the spectrum. The WC puts out a good deal more blue and cyan light. Outdoors there's lots of greens and reds (green= grass, leaves, red= dirts, treebark, animals), and not a whole lot of blue to speak of. What you see in reality is whatever light gets reflected off of a surface, so given two 100 lumen lights in cool white and warm white, chances are the warm emitter will let you see more outdoors. Indoors the blue appears much brighter because the white surface of the walls reflects most of it back to you. Also like in the bunny example, because there's more green and red reflected from the environment around the rabbit, it increases contrast, making it easier to see. (Edit: or more red from the rabbit and less from the environment, I was thinking white rabbit when I real that the first time)

Fear not with white wall hunting. At night, unless your eyes are adapted to a cool white fluorecent the 5A led will have a pure but "gentle" white color. If you get used to the warm emitter's color a normal LED that used to look white is suddenly glaringly blue. Compared to noon daylight it will have a slight pinkish cast to it. Side by side with an incan it will be unmistakably white.

Odd thing is, a few years ago, we were getting ticked off at the yellowish greenish tint (akin to the "sickly yellow" incans) and here we are looking for lights to replicate the "sickly yellow"

I have very bad eyesight, and perhaps that's why LED lights work better for me regarding colors.

The challenge: take three pairs of socks of the same size/style, but one pair black, one dark brown and one dark navy blue. Now mix up the six individual socks, and alternating between incandescent and LED lights, sort them back into matching pairs. What works better for you?

thanks for the answers and for the link in the LED forum, it's great!

GreyShark said:

...as much of the full spectrum as is practical to approximate what we're used to.

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So, if there were a LED covering all the spectrum it would seem purely white and would allow us see every colour perfectly, right? Is it possible to make this kind of led's? Can I add this dream to my dream list of the perfect flashlight (hundreds of lumens, powered by 1AAA battery, runtime of weeks ecc )?

I too used to appreciate a nice cool bordering blue LED tint but after the Inova T2 came out with it's creamy white tint I came to appreciate it much more in outdoor activities.

Warmer tints also tend to cut through fog better than cooler tints for the same reason that Incan lights are (were) usually better for cutting through fog than LEDs are (used to be).

"Apparent" brightness has nothing to do with how many lumens are coming out the front of your flashlight, but has to do completely with how many are reflected off the scene and back at your eyes.

Natural environments has lots of red content. If your flashlight is not putting any out, then nothing is coming back at you ..... which means that the blue, green, etc. hitting that red is absorbed.

Neutral whites are a good trade-off between lumens and colors that appear in typical outdoor scenes both natural, i.e. trees, dirt, etc. and man made, i.e. what appears along a road. Neutral whites were initially developed for the automotive industry.

Semiman

For me it has more to do with the CRI, than the fundamental color tint. IMHO warm tint LEDs can't come close to incans in this one aspect.

http://en.wikipedia.org/wiki/Color_rendering_index

Millions of years of evolution. Your eyes are, after all, very used to that big warm incandescent in the sky.

kramer5150 said:

For me it has more to do with the CRI, than the fundamental color tint. IMHO warm tint LEDs can't come close to incans in this one aspect.

http://en.wikipedia.org/wiki/Color_rendering_index

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dear God almighty...i thought i was the only one. i absolutely hate the excessively cool emitters of a few years back but i still prefer neutral or cool white tint (like many of the R2s) to warm tint, specifically 'LED' warm tint.

judging an emitter to be 'warm' or 'cool' is obviously relative...i used to think my Olight M20 w/ the R2 had a somewhat cool tint until i received an order from DX for several low cost dropins and lights, virtually all w/ CREEs. the only 'warm' emitter i own (as most people here would classify as warm) is a Q4 5A pill from Dereelight. i was pretty disappointed. i still kick myself for not thinking of it beforehand, but warm emitters (just as neutral or cool ones) have a very narrow range of wavelengths being produced. this is in complete contrast to an incan. shining that warm emitter into the woods i can see why there would be a preference for warm tint but to me its not worth the loss of output. the glare that comes back to you off the leaves and trees still looks artificial. i probably won't pursue another warm emitter until somebody develops one that can produce light that covers a much greater range of wavelengths.

in any case, if you want to see nature in its most undisturbed form, then go out when the sun is still up or go out at night and leave your light off. i realize thats kinda silly, i would want a light w/ me but if color rendition is paramont then there is nothing that can compete w/ incan...for now.

In the same way, I don't mind a cool tint which has 100CRI. Daylight when shrouded by clouds can be pretty cool. (For me personally, I love the 100CRI of my incans but can't stand their 3000-4000K color temperature, and I hate the low CRIs of slightly-warmer cool tints, but would prefer their 5500-6500K color temperature)

Ideally, I'd love a range of tints but all with 100CRI.

Does anyone have that graph of the spectrum curve of cool white LEDs vs Warm high CRI tints? That'd be useful. i think the led museum has it but his site has always conflicted with my eyes and brain.

try this page.. it compares cool vs warm LED lights.

From Spectrographic analyses, pg. 4 post #8 rehosted.
Unknown-type cool white LED.


The_LED_Museum did a spectrographic analyses of a neutral warm white Q2 5A bin for me a couple of years ago.
From Spectrographic analyses, pg. 3 post #154 rehosted.


Outdoors leaves and grass is green, tree trunks and mud trails are brown, very little blue.
The excess blue of cool white LEDs casts a haze over everything reducing clear colour rendition.

Indoors (and downtown concrete buildings) most walls are white or gray. The excess blue of cool white LEDs make the walls look whiter.

So warm white outdoors, cool white indoors unless your walls are wood paneled.

Thanks, LEDNinja, for those graphs. Very concrete representation of the difference. As can be seen from the graphs, neither cool nor warm LED's are necessarily "better" at rendering the full spectrum of colors accurately since both are deficient in certain areas.

For me, I just dislike cool tints because it bothers my eyes. Can't put my finger on exactly what bothers me, but could be the big blue spike in the spectrum. I suppose another option for me would be to just wear Eagle Eyes or BluBlocker sunglasses whenever I use cool LEDs!

OceanView said:

I just dislike cool tints because it bothers my eyes. Can't put my finger on exactly what bothers me, but could be the big blue spike in the spectrum.

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The spectrographs are very useful. You are right about the blue spike bothering some people - blue light tends to dazzle and glare, and the extra blue in the LED spectrum can give the impression of being brighter than it actually is. For other people, however, too much yellow/red can be annoying, which is why they prefer LEDs to Incans. It is very subjective.

Leaving aside these personal preferences, an object of a certain color will not show up properly unless it is illuminated by light of that same color. True white light contains all color wavelengths, so it will illuminate all objects. Most LEDs are weak in red, so objects that contain red are not properly illuminated and typically appear a rather dark muddy brown. That is why a purely blue light is useful for spotting blood traces - the blood is not illuminated and appears black. Equally, a red light will be no good at illuminating a blue object.

It's just a question of what you like and what you need. Everyone is different.