Interest Thread; Malkoff M61 New 519A 4500k / 5700k 9080 *Group Buy 2022!*

LEDphile

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Sorry about that haha. I’ve had some low quality Samsung “CRI” emitters with puke green tint. :D
Color point ("tint") and spectral power distribution ("CRI") are mostly uncorrelated, so it's certainly possible to have LED output along the blackbody curve ("good tint") but with poor color rendering, and also to have (different) LED output that is off or to the extremes of the blackbody curve ("poor tint") but has good color rendering.

In fact, I witnessed a demo several years back of a set of colored objects in front of a white background, all lit by a multi-channel LED source. The light source was controlled such that the colored objects were changing color, yet the background was not - this was a realtime demonstration that tint and CRI can be decoupled.
 

DaveTheDude

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OK, so where do I sign up? If Illumination Supply or some other worthy entity is on this, please let us know. I have several Malkoff lights and multiple light engines for 6P hosts, all have performed superbly over the years. Adding one or two more light engines that offer exceptional color rendering is a no brainer for me. Count me in.
 

kerneldrop

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I was alread on board using the IES TM30 standard instead of CRI before, but when I got my first "high CRI" LH351D I was floored how awful it was.

I'm confused with CRI...

The 3500K 219b turns my skin rosy.
4000K SST does not change my skin to rosy, but it's a different color
5000K 351 does not change my skin to rosy, but it's a different color
4000K 219b does not change my skin rosy, but it's a different color
I have a 4500K in something hiCRI and it's a different color.
My wife has an insanely expensive medical high CRI light and my skin is a different color under that.

So based on my expert level scientific testing, high CRI is a scam.
 
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dotCPF

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CRI is relative to the color temperature it is presented at.

Mixing HCRI tints will result in a loss of CRI as a result, I believe.
 

kerneldrop

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CRI is relative to the color temperature it is presented at.

Mixing HCRI tints will result in a loss of CRI as a result, I believe.

And this makes sense to me, but someone here used fancy words and explained how CRI is not affected by tint.

But my publication-worthy-experiment proved that to my eyes CRI is relative to color temp.

Some modders believe you can maximize CRI by mixing LED. But you’re still just changing colors…

We circle back around to CRI being a scam.
 
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defloyd77

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I'm confused with CRI...

The 3500K 219b turns my skin rosy.
4000K SST does not change my skin to rosy, but it's a different color
5000K 351 does not change my skin to rosy, but it's a different color
4000K 219b does not change my skin rosy, but it's a different color
I have a 4500K in something hiCRI and it's a different color.
My wife has an insanely expensive medical high CRI light and my skin is a different color under that.

So based on my expert level scientific testing, high CRI is a scam.
You can't compare one tint to another tint with CRI. In order to make a valid comparison, you need to compare 2 lights of the same tint and color temperature but different CRI. You'll soon realize one looks quite lacking, especially reds.
 

kerneldrop

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You can't compare one tint to another tint with CRI. In order to make a valid comparison, you need to compare 2 lights of the same tint and color temperature but different CRI. You'll soon realize one looks quite lacking, especially reds.

So should CRI be described as... making colors pop, rather than bringing out accurate color renditions?
 

dotCPF

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> how CRI is not affected by tint.

CRI can be 95 at 3000K or 5000K, hence "CRI is not affected by tint"

HOWEVER

MIXING light sources is not "affecting" tint, you are changing the actual source of light and thus overall spectrum. IDK who thinks what exactly but we can measure this, I believe that that I have seen tests by more knowing/savvy individuals like Muakka/ Andy Z to show evidence that tint mixing lowers overall CRI. (at least I believe this to be the case, I cannot find the thread quickly....)


Think about it this way: the final CRI of what you see is governed by the totality of light present. Two seperate sources at equal CRI but at different K temps does not "Add" but "averages". As CRI is an average of averages, you have to look at individual color ratings (like R9) and average all of those which will always lower the score of the higher rated LED.
 

dotCPF

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So should CRI be described as... making colors pop, rather than bringing out accurate color renditions?
Kernal I feel like our brains are wired similarly, invert the terms in your brain. :)

CRI quite literally means "color rendering index" because CRI describes how accurately a light source displays a color.

I would say that *tint* makes colors pop (like cooler tints make blues pop) and warmer K temps make yellows pop, but would inversely mute blues.



edit: I would like to add I find this most amusing and am enjoying conversing with y'all this morning it's been a while!
 

fulee9999

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CRI is relative to the color temperature it is presented at.
Not really, CRI is unrelated to CCT. You can have a 2000K high CRI and a 6500K high CRI light soure ( like the sun for example ) and they have the same color rendition but wildly different color temperatures.
Mixing HCRI tints will result in a loss of CRI as a result, I believe.
You mean mixing a 4000K HCRI with a 2500K HCRI? Why would it make? Using different light sources to illuminate an object is an additive function, you can never subtract light. That would mean you can have a flashlight that makes darkness. Even though light is a wave as well ( while being also a particle ) you cannot subtract light intensity.
So should CRI be described as... making colors pop, rather than bringing out accurate color renditions?
Well yes and no... That's why I quoted using the IES standard, because in it you have a better understanding of what sort of light you're dealing with. CRI is a metric of how accurately a light source renders the eight defined colors compared to a black body radiator by the standards.
CRI does not talk about how much a certain color "pops", only how ( lacking a better term ) well represented it is.

While the IES standard separates these two, how much the color pops, and how accurate it is compared to a perfect light source. A great representation is in the standard's description:
1643302956684.png


Here you can see the Y axis, gamut, that how much a color pops. The X axis is fidelity, or how accurate the color is.
So for example an Rf 70 but Rg 120 would mean that the source is pretty accurate but just way cartoonish looking, this is by the way what light source usually theme parks go for. Where you don't need perfect accuracy, but you want the vivid colors of a fairy tale.

Also, the IES TM30 contains waaaaay more info about how you should imagine a light source, for example here is the TM30 data for the 4500K SST20:

1643303192088.png


You can see that it represent the colors well ( Ra 96 ) the gamut - or how much the colors pop - is 95 (Rg value ) and you can see that almost all the reference colors are rendered accurately ( color fidelity chart at the bottom ).

Meanwhile, if you check a Samsung LED:
( this is a 6500K "high CRI" LH351D, claimed to be 90+ CRI )
1643303291473.png


You can see that the average color rendering is in fact 58 (Ra), the gamut ( how much color pop ) is -18 (Rg) so basically it washes out the colors, and you can clearly see that the colors are waaay tint shifted and not really accurate.



I might have gone a bit off topic, but thank you for coming to my TED talk....
 

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