HCRI & Eyes....

hello folk's -

HCRI eyes help needed!.

they say (according to google stuff), 4300 k is best for the majority of our eyes, then If so, would this matter if a flashlight made with say a 4500 - 5000 HCRI be just as good as it has HCRI to compensate?...if that's correct, or are are these two different matters?.


I also see cars with the 4300 set up, which is best for road use, I assume, but then why do some flashlight manufacturers make higher brighter lights, like BMW at 5000k, & forgetting our eyes need to see better?. is that where HCRI comes in to alleviate this ?.


so now even BMW have 5000k lighting now on new models...No HCRI ?. so how is that good for our eyes?.
they say 4300 gives out more light too, but my 5000 LED pd32ue seems brighter.


i know all our eyes are different, but the majority...




thanks.

:thinking::thinking:

CCT is primarily dependent on your own taste and preferences. Everyone has different uses and taste for CCT. However, CRI is not determined by CCT. I've read somewhere that McGizmo made a cool white, high CRI light that got burried in the forum somewhere.

When I modded an old light for someone into a 3000k XML, I love that tint when pushed at 3a. It's incan yellow on low and just whitish yellow on high.

Color temperature (CCT) and rendition index (CRI) are two different things.

The temperature, measured in Kelvin and ranging from sub-3,000K for warm to greater than 5,000K for cool, defines the tint.

CRI, on the other hand, grades how well a source of illumination can render the visible color spectrum. 100 is the point where all colors are clearly reproduced to match the colors represented in natural daylight condition with full sunlight. Lower grades mean that the colors have less contrast and, subsequently, are harder to distinguish. Incandescent bulbs typically have 100 CRI, because they emit full spectrum range. LEDs and fluorescent bulbs, on the other hand, are graded lower since they emit narrower range of spectrum.

Now, when it comes to LEDs, having a warm or neutral tinted emitter doesn't necessarily mean higher CRI. For example, Cree's high CRI LEDs are very warm at around 3,000K, and are typically graded with 90 CRI. On the other hand, we have Nichia 219 with CRI of 92, but with a cooler (but not cool) color temperature at 4,500K. The quality of phosphor play a huge role in this.

LED manufacturers use color phosphors to change the color temperature and improve CRI, which also has the result of degrading the overall performance and, thus, lower flux bin. This is why you typically see LEDs with warmer tint end up performing less than the ones with cooler tint, because the phosphor blocks a percentage of the light produced by the emitter.

Also, it is completely possible to have a cool white LED with high CRI, and they do exist, just not widespread due to lack of interest.

Odd enough, Nailbender managed to get a 90+ XM-L @ 4500k CCT. I didn't believe it at first but I dropped by and to my surprise, it was there. I want one but am too broke to buy one. Maybe I'll ask someone to buy it for me and I'll do some dirty work for him or her

thanks, wouldn't the nichia 4500 be that little bit better at 92CRI rather than the XM-L?.
between these two, which one?. why?.
seems everyone likes nichia.

thanks.

I tried both and I like the 3000 Kelvin high CRI Cree better than the 4200+ Kelvin Nichia 219s. But if both LEDs were ten times brighter I'd probably like the Nichia more than the Cree.

You'd have to get them in your hands first to test them out yourself. Then you'll see why more people picks the 219's over the XM-L for CRI.

It's usually tough to tell two CRIs apart. For most people in most tasks, any fluorescent over 80 CRI and any LED over 70 CRI is adequate. For tasks where color is important (Cooking, graphics, design), you'll want to go higher. But CCT is quite noticeable, as is tint (Which is separate from CCT).

What is the best CCT for your eyes? It depends. In the range of 4000-6000K and adequate brightness, human vision is very good and quite sharp. In the 2300K to 3500K range, some cues your eye expects are usually missing, leading to over dilated eyes and blurry vision.

For driving, glare is a failure of equipment. High CCT can cause glare, and requires more careful light design to avoid it. BMW and a few other companies do so successfully, putting a false prestige on high-CCT headlamps that may not really work better due to CCT. In other words, the CCT is an aesthetic choice with design tradeoffs for the company.

Good headlamps in good condition work well because of light distribution, not especially high output or a particular CCT. I have fist-sized flashlights that outmatch high beams, but the flashlight would make an awful driving beam regardless of CRI or CCT.

High CRI is pleasing to look at. For color-matching it's important. For object-detection, it may not be. It is an aesthetic choice with design tradeoffs, usually about 2% lower output per point of CRI*.

*Claim sourced from 'Companies request lower EnergyStar standards for High CRI lights'

nice explanation there AAS. thanks.

Small differences in lumens, tint and CRI doesn't matter IMHO.
We CPF people might sit and compare beams and notice small differences but in real use it's not noticiable.

I have 3 Preon 2, one warm white, one HCRI and one neutral white.
I can hardly see any difference between the ww and the HCRI when I shine the both on the wall or around in my room at different objects.
If I just take one of them and use it I can not see if it's the ww or HCRI (unless I look at the flashlight itself, one is black and the other Ti)
These two lights are used at work indoors where the tint blends well with the incan light. In other applications I find them to warm.

There are also flashlights that doesn't have specified cri but can be very pleasant anyway,
My TK20, 4sevens mini123 and mini AA in nw (first batches) have very "comfortable" light, I guess they have a decent cri
My Xeno E03 nw (the first one, xp-g?) on the other hand has a very "flat" light that I guess is lower on the cri scale.

The tint that is percieved as the best is different from person to person and for one individual it differs from situation to situation (for me at least it does).

If there is ambient incan (-like) light usually nw works best for me. If I want to use my flashlight to light up dark spaces in daytime usually cool white looks better. Most of the time I prefer nw when I use lower levels but +100 lumens my cool white lights look nice.

I rather live with a less perfect tint than with a bad UI or other qualitys of the light.
My overall preference is around 4300-5000. Some cw lights are good but if it get's to cool it's not good at all.
If it wasn't for the (in my eyes) bad UI with mode memory I think the PD32UE that you have would be one of my favorite ligths.

Regarding the CRI I guess it's not any con to get a higher CRI but if it's 85, 90 or 93 is probably hardly noticable in ordinary use.

TweakMDS used and explained the term measurebate in one thread, what it means in the photography word.
I think that was a good and telling word and I think that can apply in these discussions also.

The Nichia 219 LED has a warmer, Opalescent color. The XM-L NW has a greenish tint with a slight hint of yellow. And they're both rated at 4500k CCT with an AR coated lens. The high CRI matched with the 4500K CCT does not make my eyes squint from over-exposure. That's just my personal preference and eye sensitivity.

Here's a beamshot comparison of the two 4500K CCT lights with a CW in for kicks:
http://www.candlepowerforums.com/vb...c-D25LC2-W-219-Stubby-D&p=4123530#post4123530

I've read several papers (PDFs actually) and it seems that CRI isn't suitable to evaluate LEDs. It's more than half century old testing method but so far the only one.

A quote from http://www.dominant-semi.com/userfiles/file/Color_Rendering_Index-VerA.pdf

Summary
There are multiple publications have pointed out the inadequacies of the CRI metrics to quantify the true color rendering effect especially for solid state lighting. Currently several organization including the CIE & US Lighting Research Center is still in the midst of developing a better measurement method to replace existing CRI metrics. Until then, lighting designer is advised to base on their own judgment and actual illumination comparison for LED light source selection instead of the measured CRI value.

Click to expand...

I also recommend reading:
http://cool.conservation-us.org/byorg/us-doe/color_rendering_index.pdf
http://www.gtilite.com/gti-pdf/Technote-30.PDF

Tiresius said:

The Nichia 219 LED has a warmer, Opalescent color. The XM-L NW has a greenish tint with a slight hint of yellow. And they're both rated at 4500k CCT with an AR coated lens. The high CRI matched with the 4500K CCT does not make my eyes squint from over-exposure. That's just my personal preference and eye sensitivity.

Here's a beamshot comparison of the two 4500K CCT lights with a CW in for kicks:
http://www.candlepowerforums.com/vb...c-D25LC2-W-219-Stubby-D&p=4123530#post4123530

Click to expand...

The XM-L neutral white range has quite a lot of color bins. These range in tint from pinkish to blueish to purplish to greenish. I'd like to add that they're quite a lot better than LED tints used to be. CCT and tint are not dependent on one another. Depending on which tint bin you pick (Letter-number, like 5A being deliciously white-yellow), and which space you get in that tint bin, and the current and temperature and optics, will all affect the apparent tint. Heck, the Nichia 219 changes its characteristics quite a lot at low drive current and odd temperatures.

Photographs do a poor job of showing what a light looks like in real life. The spectral distribution of a light source is captured in a sensor with filter bands, converted to digital values that cut off the dynamic range beyond about 3 stops, and then altered by the photographer for 'what it looked like to me' and your computer screen by its settings. So dynamic range is compressed and tint is exaggerated and distorted. Proof? Take a digital photo of a filament bulb next to an LED, with daylight shining in. It will look harsher and darker on the photo, with crazy blue LED highlights and orange filament light.

Edit: And CRI isn't especially good to judge light quality. But it's one number! It compares to a black-body radiator, which we know isn't ideal for color perception. There's plenty of other standards, but they aren't one number. They include ratings at various extreme colors, like deep red discrimination.

neutralwhite said:

hello folk's -

HCRI eyes help needed!.

they say (according to google stuff), 4300 k is best for the majority of our eyes, then If so, would this matter if a flashlight made with say a 4500 - 5000 HCRI be just as good as it has HCRI to compensate?...if that's correct, or are are these two different matters?.


I also see cars with the 4300 set up, which is best for road use, I assume, but then why do some flashlight manufacturers make higher brighter lights, like BMW at 5000k, & forgetting our eyes need to see better?. is that where HCRI comes in to alleviate this ?.


so now even BMW have 5000k lighting now on new models...No HCRI ?. so how is that good for our eyes?.
they say 4300 gives out more light too, but my 5000 LED pd32ue seems brighter.


i know all our eyes are different, but the majority...




thanks.

:thinking::thinking:

Click to expand...

Yeah, the Tint (ºK) has nothing to do with accurate color rendition, and, cooler tints are brighter for a given LED.

A tint is MOSTLY about personal preference for how you want things to look. If you want things to look yellower, you want a warmer tint. If you want to SEE IF something is there, for the same LED choice - you generally go with a cooler tint to get more lux on target...as the cooler the tint, the more lumens a given LED can typically produce.

If you need to know the color accurately, tint is not the answer per se...as some tints are better for some colors, but worse for others....you trade one part of the spectrum for another.

CRI, is supposed to describe the color rendition...and it does mostly, but, not perfectly. It does give a RELATIVE idea though, if comparing the CRI of different lights, the higher CRI will tend to be more accurate at least.

After that its about priorities. SOME work I do requires either good rendition, or, exaggerated rendition of frequencies of interest. I do forensic investigations for example, and use UV light (An extreme frequency choice for the example) because certain things about my target are DE-emphicized, and certain things are exaggerated....so that the part I am LOOKING FOR is going to stand out.

Its the same for disaster response/search work. The likelihood of finding someone mostly revolves around separating them from their background. Its a combination of color and lux on target. If I have night adapted vision, I can't see color really anyway, so LUX is king. If my eyes are not night adapted, and I am relying only upon the light's beam I am carrying to see what's out there, I can still distinguish colors. For some searches, night vision is a double edged sword.

If my eyes are adapted, I need less lux on target to resolve the target from its background....but I can't use color vision to see potentially useful color patterns.

If my eyes are not adapted, I need more lux on target, but, I still can also use colors to delineate patterns of interest, etc.

MOST of the time, I'll see more overall w/o color but more light on target....in an adapted state...as more lux generally helps to resolve targets better than more color does.


So, if driving down the road one night, and you don't want to hit a deer or go through a pot hole....color is rarely the top priority, lux is. As lux is the light bouncing back you your eyes, and our eyes perceive a certain frequency best...we have a better chance of seeing the deer/pot hole sooner with that frequency to work with...AND with the most target light bouncing back to our eyes.

So, as more lumens being sent out tends to produce more lux on target for a given LED/Lens combo...they pick an emitter set-up that tries to get more light to do that. This can mean the light is cooler than the optimum eye receptor range, so maximize the total lux, but not too far above that range, to maximize the optimum receptor range. (Obviously, we see in ALL the visible spectrum range too, so we see MORE if we can ALSO use other parts of the spectrum than just one band, etc)

I've just got my first Nichia 219 light and there are a few points in this thread that are now very apparent. I had the impression that the Nichia is a warm light but it isn't. So there I was expecting a warmish tint like my TK20, which some would say puts out a lot of yellow.

I like warm so I guess I was a little surprised that when I got my L3 219 and shone it on a white wall ... it looked white. What took me a little while to figure out is that whiteness is actually the whiteness of the paint on the wall, as it is during the day. There wasn't any discernible tint that I could see from the 219. So that's where I've had to come around to that way of thinking. Nichia 219 4500K does not necessarily mean a Warm tint.

The L3 219 probably has the same neutralness as my LF2XT warm. Side by side on a white wall, they are very similar but shine it on some coloured stuff, I can tell that the colours are just a bit duller on the LF2XT. The TK20 would give a yellowish glow to same colours, H51w dullish, H501w dullish with a bit more tint. At a glance, you would be hard pressed to notice the difference straight away.

That said, I don't really know if high CRI gets me as excited as most people here. Pleasing to look at? Maybe if I was surrounded by colours but I live in a rather grey surround.

Honestly I prefer the warm Cree hcri to the neutral Nichia hcri. It might well be due to the brightness, neither is pumping out insane lux and there is some agreement (and controversy) that warmer light looks or works better with human eyes at lower lux.
I put two of the Cree and two of the Nichia into a flex arm work light with an old cpu heat sink and a dimmable power controller, really nice quality lighting. I don't know how much the two types cover each others cri shortcomings but the light is perfect to me, and the warmer Cree is noticeably brighter to my eye, as well as staying on longer when the dimmer is turned nearly off -lower power needed to emit light I guess.

eh4 said:

warmer light looks or works better with human eyes at lower lux.

Click to expand...

Do you mean level at which the LED is glowing? I have to say that the low modes of the L3 219 don't seem that spectacular. As it ramps up, it gets much nicer. I think someone has shown that the CRI increases as amps increase. It may be a case of the PWM in the LF2XT, but at the low levels, I feel that the LF2XT is much nicer to look at.

The one thing that I noticed about the warm lights, such as my TK20 is that out on a mountain bike trail, I much prefer warm. I can see shadows, divots, rocks etc much better than my cool L2D. I don't know if CRI has any bearing on that.

Eh, how come no-one mentioned this yet? If you're trying to find light that looks comfortable forget the lumens and measure lux. That obviously varies wildly depending on how far the source of light is from the object illuminated but the needs do too so...

Pekka said:

Eh, how come no-one mentioned this yet? If you're trying to find light that looks comfortable forget the lumens and measure lux. That obviously varies wildly depending on how far the source of light is from the object illuminated but the needs do too so...

Click to expand...

Probably because you're talking about what is perceived as pleasant, vs what can be seen, the thread's topic.

GunnarGG said:

I have 3 Preon 2, one warm white, one HCRI and one neutral white.
I can hardly see any difference between the ww and the HCRI when I shine the both on the wall or around in my room at different objects.
If I just take one of them and use it I can not see if it's the ww or HCRI (unless I look at the flashlight itself, one is black and the other Ti)

Click to expand...

What is the tint of the high CRI light? As has been pointed out, high CRI LEDs can have warm or cool color temperature, just like low CRI lights.

One wouldn't usually expect to see many benefits of high CRI lights indoors, particularly by shining on a wall. It is outdoors where high CRI lights outshine (so to speak) similar lights with lower CRI.