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A comment on Trying to Solve the L.E.D. Quandary.

Re:Trying to Solve the L.E.D. Quandary by bhauer on Thursday October 06, 2016 @05:30PM (#12656281)
I had understood color rendering index (CRI) to be independent from color temperature. This article suggests CRI and temperature are—if not the same thing—correlated. Perhaps that is true, but I know that I have gone out of my way in the past to buy high-CRI, high-color temperature bulbs because I prefer "daylight" (~5100K) illumination. I've got some 5100K bulbs that were rated at 90+ CRI in my kitchen and I love it.
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Re:Trying to Solve the L.E.D. Quandary by Declanomous on Thursday October 06, 2016 @06:13PM (#12656572)
I suspect a lot of the R&D in LED manufacturing has been focused on bulbs which functionally replace incandescent. Creating functional replacements of incandescent bulbs is certainly a noble goal, but incandescent lights aren't uniquely suited to every situation.

For instance, I live in a row house. The south facing windows have shades over them, which I can't remove because I'm renting. This means the amount of natural light is extremely limited inside. I find that if I don't spend some time in the sun early in the morning, I feel extremely sluggish and lethargic.

Replacing the sun is really hard though. Not only does the sun have a "perfect" CRI, but it is extremely bright and provides a very diffuse light. (Not to mention, the sun is really cheap). I've found the easiest way to mimic the diffuse nature of sunlight is to have a number of light sources.

Right now, the only "sunlight" (7500k+) bulbs that I can find that are inexpensive enough to cover my living room, render color well, and are efficient enough to keep on during the day are florescent. Halogen uses too much power and generates too much head. I can't seem to find reasonably priced LEDs with a good CRI above 5000k.

I've only been able to find 2 kinds of "sunlight" LEDs. One is 75-watt BR40 (or lower wattage BRxx lights), which, as spotlights, are not very versatile. The other are "grow-lights", which I am hesitant to buy, since I have little interest in partaking in a no-knock raid at 2 AM. That might be paranoia, but I've heard stories at the homebrew/hydroponic store where I buy my homebrew supplies, and I don't think it's too unlikely.

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Re:Trying to Solve the L.E.D. Quandary by simcop2387 on Thursday October 06, 2016 @05:46PM (#12656392)
I'd say they're definitely corroloated, a really low or high color temperature bulb will go much lower on the CRI since it won't be producing as much of the other end of the spectrum. But a good temperature bulb won't necessarily have a good CRI because a middle temperature bulb doesn't have to produce all the intermediate frequencies that a good CRI bulb will have.
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Re:Trying to Solve the L.E.D. Quandary by CapitalistCartr on Thursday October 06, 2016 @05:43PM (#12656367)
CRI is different than temp. A bluish, high-temp lamp and a reddish, low-temp lamp can both have terrible color rendition. Lamps come with a chart, like here:

http://www.topbulb.com/color-rendering-index

that graphically shows the color distribution. Temp is where on the visible color spectrum its focus is.

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Re:Trying to Solve the L.E.D. Quandary by l33tbro on Thursday October 06, 2016 @07:34PM (#12657002)
Beware of the hype around "high CRI". It's more of a global snapshot of a light's various colour rendering abilities. I've seen some "high CRI" bulbs with shockingly bad spikes in certain colours. What you really want to pay attention to is the individual R1-R14 values and make sure there's no dips.

For example, if you're looking to replace your household tungsten lightbulbs then it's really important to pay attention to the R9 value that your LED ilght has (1), as it refers to the red value being emitted by the bulb and is what affects skin-tones.

And, yes, CRI is completely independent of temperature. You can have a daylight or tungsten LED bulb with completely varying CRI values.

(1)http://www.eyelighting.com/resources/lighting-technology-edu...

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Re:Trying to Solve the L.E.D. Quandary by helthanatos on Thursday October 06, 2016 @07:00PM (#12656840)
I very much prefer a more yellow light than a more blue light. I feel like I'm in an asylum when I'm somewhere that has real blue lightbulbs. Shouldn't something that only emits one color have a perfect CRI? Or are lightbulbs assumed to mimick the sun and that's why they don't have perfect ratings?
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Re:Trying to Solve the L.E.D. Quandary by ScottBurson on Thursday October 06, 2016 @06:23PM (#12656618)
CRI and color temperature are not the same thing, but this isn't the first time I've seen people get them confused.

These 5100K, 90+ CRI bulbs in your kitchen -- are they fluorescents or LEDs?

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