For me, 3000K is nice and soft on the eyes, especially in very dark places. I can stare at 3000K and scrutinize visual details very comfortably. 4000K is good, 4500K is OK. 5000K is beginning to get too harsh for my eyes to look at.
The problem with cool white is that it tends to wash out colors, making it harder to distinguish and determine what you’re looking at. So in a sense, although cool white can “light things up”, it does a poor job at letting you see what’s really there.
When I first got into high powered flashlights I was all about cool white tint and the most lumens available. It’s been recently I prefer nw tints. Even at the expense of a couple hundred lumens.
Miller is 110% correct. I could shine my 1400 lumen xpl hi cool white about 60-70 yards up in a tree and could see eye balls but not make it out the animal definitely. I could take a 1050 lumen warmer tint light. And see exactly what it was a raccon like I thought. Same light both x6s. So its not like comparing two different light models. Both x6 with smo reflectors. One with q xpl hi cool white the other with a xpg2 s4 0d dedomed. Even my other warm lights you can see much better detail at what your seeing especially as the distant increases. I still use my cool white lights. Just depends on the tasks.
I prefer a warmer to neutral tint, with a high CRI of course. The tint shouldn’t really effect the throw of a light, other than the slight drop off in total output from the extra phosphors to get the warmer color temps. The higher color temps seem to wash things out and hide some of the details that I need to see.
Showing my ignorance here but if you don’t ask the question you’ll never learn … what’s CRI???
CRI is the ability for a light source to reproduce the actual color of an object. Check this page for some examples of various CRI levels: DonsBulbs Lighting Design
For indoor use I prefer anywhere from 4000 or 4500K. Both give a fairly white beam but with enough tint to provide a pleasant experience. 3000K looks downright orange and I find it harder to distinguish things. A bit cooler is better.
For outdoor use, even 4000K can sometimes feel too cool. 3000K looks much better.
As you say it’s there to do a job but what the job is can affect which tint is best.
Can filters bring a cool kelvin temperature light down to a warmer one, and if so could it be reversed?
In theory a filter could be designed to remove the bluer parts of the spectrum in such a way to make it a warmer temperature.
In theory a filter could also be designed to remove the redder colors more and increase the color temperature.
Both would probably be fairly inefficient because they would be absorbing or reflecting the colors they remove.
Thank you.
Absolutely, in fact they already exist for the theatrical and film industries. Most of the time we use gel which is thin plastic sheets, you can also get a lot of colors in dichrotic glass for long term use. The problem is they are very inefficient. What most people would probably want is a quarter cto gel like Lee 206, it would take you from 6500k to 4600k, and let about 79% of the light through, with the rest turning into heat. In the theatrical world it’s not a big deal it’s just part of what it takes to get the look we want. The really saturated colors like deep reds and blues can have as low as a 2% transmission rate.
Some other examples are:
A full CTB (color to blue) like Lee 201 takes a 3200k halogen source and turns it into 5700k, the problem is it only ends up transmitting about 34% of the light that passes through it. The rest of it gets turned into heat.
A half CTB would get you 4300k, but would only let 55% of the light through.
Going the other way a full CTO (color to orange) like Lee 204 would get you from a 6500k arc lamp to 3200k and let about 55% of the light through.
A half CTO gets you to 3800k and lets about 71% of the light through.
Thank you for the detail.
All tints have a purpose, and can complement each other well for photography. The below photo uses:
3000k warm white - background - Lumens Factory Seraph SP-6 with high-CRI module
5000k neutral white - backlighting, illuminating most of foreground - Convoy L6
6500k+ cool white - headlamp - Varta 5-LED Indestructible Headlamp
If I’m going for fullest output, yeah, I’ll go with cooler tint. But for something I’m actually going to use, neutral and warm all day. All I had when I first started were cool tints. For me, right around 4000K with a tad of rose is perfect. I gambled on an XHP50 with 5D0 tint. I’m glad I did. When my batteries are done charging I’m gonna take it for a walk around the yard tonight. Imagine that light from the sun just as it’s about to set and it sort of casts a rosy glow on everything.
Dude, that is awesome! Doesn’t even look real!
I usually prefer 5250 - 6500K… Neutral up to about mid-cool.
I do not like the extremes, when it yellows on the warm side or blue-greens on the cool end; I’m out. 
All between 3000k to 5500k is good for my eyes. The rest is junk. 
Serious academics are full of Shit! 
I agree with this for flashlights, in our house we have 3500-3750K in the lights (all LEDbulbs and spots)
find 5000-5500K ideal. No blue and no yellow/amber (yellow amber being as annoying as blue imho)
But thanks for the choices!
Tint is used rather broadly on flashlight boards. It is actually a technical term that is separate from Color Temperature (CCT)
For example, Look at the CCT 5000 Kelvin below.
Some people call this the beginning of Cool, but it would also be correct to say it is Warmer than 6000k. Confusion is eliminated by referencing the Color Temperature Number. Warm, Neutral and Cool are also valid terms but I want to stay focused on Tint first.
Look at the 3S Tint “bin” (box). It is a 5000k(+) Color with Yellow Tint. Compare that to the 3U box. It is a 5000k(-) Color with a more “rosy” tint.
LEDs do NOT have all the colors of sunlight. LEDs start out making a lot more blue than red. To make an LED produce Red, requires coating it with a phosphor that produces Red. In the process the total amount of light making it out of the reflector is lower when a phosphor coating is added to an LED. You get a light spectrum closer to sunlight by using a phosphor, but you give up lumens.
Now for sunlight. On the Color and Tint chart below there is a faint Dotted Line, called the BBL (BlackBodyLine). This is the IDEAL color and tint of an LED to MATCH sunlight at that given Color Temperature. Sunlight at Noon has a different Color Temperature than at Sunset.
For any given Color Temperature, most people will prefer the LED Tint that is closest to or BELOW the BBL. That is why we hear of people saying they like the Rosy tint of a Nichia (generally this means the LED has a phosphor coating that increases RED output.) CRI (color rendering index), goes UP as RED output goes UP. If you start with a Cool white 6000K LED, and add a phosphor to increase red output, the CCT will drop. For sake of example, in the case of a 4500K 90+ CRI Nichia 219b, the lumen output will drop along with the CCT (Corrected Color Temperature).
So, a 6000K XP-G2 will be Cooler and have more lumens than a 4500K Nichia. The Nichia will have higher CRI, will show reds better. The XPG2 will be brighter. For sake of reference, the Lumintop Tool with XP-G2 has a CRI of about 70, a Color Temperature of about 6000 kelvin, and will produce 110 lumens on high. The same Tool but with 4500k Nichia is 90+ CRI and produces 80 lumens. The 30 lumen difference is significant. If you had an 80 lumen light, and you could get an extra 30 lumens out of it, that is an increase of 38%!!!
So a lot of flashlights are sold based on having the highest Brightness. It drives the consumer market. That is how people compare lights, at first. After a while, some flashaholics begin to realize that cool white light does not really show the true color of some things very well. They then begin to appreciate the High CRI LEDs, for which the term Nichia is often used, because Nichia is like the Kleenex of high CRI LEDs. It is what they specialize in, their market niche. Anytime someone says Nichia, the implication is High CRI of 90+, and along with that it implies a warmer CCT than Cool White (which most people would agree includes the 6000k CCT). People also know that Nichia means less bright.
It is a tradeoff, if you want more red, you give up some brightness and some coolness.
Now for what makes some people prefer 6000k over 4500k
Someone looking for a person, or their dog, 50 feet away in the backyard, will prefer the 6000k light. They want the most brightness (which also means the light will have the most throw). They want to see far, and brightly. In this use scenario, more lumens is more useful, than more Red rendering.
otoh, someone cooking a steak in their backyard, cutting it open to check if it is done, will prefer the High CRI light, even though it is less bright. At arms length they do not need maximum brightness, but they do need to see if the meat looks red or not. This scenario favors the Nichia.
so, which “tint” (actually color temperature), someone prefers, depends on how close or far the target is. Whether they need to use maximum or if medium is enough. And whether they need to see large forms, or want more emphasis on the ability to show reds.
This is where the ambient light comes into play. During the day, say 12 noon on a sunny day, my brain and eyes are adapted for bright light at high CCT. If I want to use a flashlight to look at things under the hood of the car, I will prefer a CCT that is in the 6000k range, over one in the 4500k range. The 6000k will seem more white, the 4500k will seem more orange. And the 6000k will be brighter, which is more necessary, when my eyes and brain are in ambient sunlight adaptation.
So, mechanics, and people who work under cool white light, will prefer 6000k light.
otoh, my house lighting is 3000k incandescent (incandescent light is more full spectrum than LED lighting). After being under 3000k lighting for an hour or more, my brain and eyes adapt to that Color Temperature. The brain basically does what a camera does when it sets its white balance. In this case 3000k becomes the “normal white” for that ambient Color Temperature. Now if I turn on a 6000k LED flashlight, the beam seems very blueish and glaring. Where as a 4000k LED will seem whiter and brighter than ambient, but not so harsh as 6000k
For someone like me, that uses a small AAA flashlight around the house in the evening, to look for some wiring behind the TV, or look for some shoes at the back of the closet, my 3000k or 4500k flashlights will be preferred, over a 6000k light. Because the ambient light I am operating in, has set my brain’s white balance to a warmer Color than Sunlight at noon.
Since I dont have a dog, do not work as a car mechanic, and do not use a flashlight to hunt for intruders in my back yard, a 6000k light is not my priority. Since I do like to have a small AAA in my pocket, that I can use to check if the steak is done when grilling in the dark, or to find my red slippers in the dark corner of my closet, or to do other things at arms reach where seeing red things correctly matters, I “prefer” a 3000k or 4500k led. I also want them to be High CRI. Since High CRI is a priority for me, I mostly avoid lights with 6000k Color Temperature. Usually a 6000k LED will only have about 70CRI. It will not produce enough red to show red objects as red. They will look more brownish than under full spectrum sunlight, or incandescent light.
Bottom line, the Color Temperature we prefer, changes with the Color Temperature of the background lighting our brain is adjusted to at the time.
Whether or not one prioritizes High CRI, depends on how important the ability to see red is, for a given flashlight application.
Looking at food with a flashlight will favor High CRI choices. Looking at things at close range, will favor low brightness and High CRI. Looking for a red tabby cat up a tree in the dark will favor higher brightness and High CRI. Looking for a black labrador running around on a football field in the dark, will favor high brightness and CRI will be a lower priority.
jon_slider
Thank you for the detailed explanation; I found it very useful. 
