High CRI = low color temp.?

Does cool white high CRI LEDs exist?

CRI is a measure (literally) of how closely a non incan source correlates to an incans ability to render color. The farther from warm the color, the lower the CRI score, so warmer implementations are easier for getting high CRI scores.

yliu said:

Does cool white high CRI LEDs exist?

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The Nichia 083 is probably the closest thing at the moment.

Stanley LED has some cooler high CRI LEDs. Can't find them locally and shipping makes them grossly expensive.
http://i-led.co.uk/LED_Systems/ILS_Products/Power-Star.html

Problem with CRI is that CCT and efficiency take a hit. Maybe in a few years they'll increase efficiency enough to make up for the lumen hit for CRI.

Luxeon Rebel is pushing 80-85 CRI up to 5000K.
http://www.philipslumileds.com/products/luxeon-rebel/luxeon-rebel-white

Problem with Nichia 083/183/119 is finding them in stock at a low enough volumes.

And, then there are the non-flashlight LEDs....
http://www.sharpleds.com/zenigata.html
http://ce.citizen.co.jp/lighting_led/en/products/CL-L234A.html
http://www.edison-opto.com.tw/01_led_products_detail.asp?sn=133
http://ledlight.osram-os.com/2011/04/high-color-rendering-index-cri-led-lights/

The question is, how cool do you need it to be? how much CRI do you really need?

I found these: http://www.sharpsme.com/lighting/led-modules/GW5BNC15L12

6500K and 90CRI. I would love to see what they look like. They have all kinds of temperatures listed as high CRI.

Interesting, from the datasheet it looks to be 30 separate LEDs in one package. Would be interesting to play around with, but I suspect it won't be so useful once you need to focus it.

As a pure flood though it might actually be quite good.

Edit: Efficiency based on that page looks like 51.7 lumens/W when run at 360 mA. Still taking a fairly large hit for good CRI.

It's funny, because I don't really understand the tint issue. For me, tint is only a concrete issue when two lights of different tint are side by side. Otherwise, all these tints are still very white.

I love the warm XPG high CRI LED. It's a fine tint and only seems warm when I compare it side by side with other older lights I own. Alone, this light is just a great useful light with pretty decent color rendering.

I am not a guy who understands the debate regarding tints. For close up work where color matters (BBQ at night, wound inspection, or table light), the quality of light is so much more important than whether it's 5000K or 4000K IMHO. And accordingly, for throw, who needs high CRI light at 100m?

That being said, the Nichia 083 is as close to sunlight tint with High CRI that's currently out there, I think. Too bad it's output is so low.

obi

Obijuan Kenobe said:

It's funny, because I don't really understand the tint issue. For me, tint is only a concrete issue when two lights of different tint are side by side. Otherwise, all these tints are still very white.

I love the warm XPG high CRI LED. It's a fine tint and only seems warm when I compare it side by side with other older lights I own. Alone, this light is just a great useful light with pretty decent color rendering.

I am not a guy who understands the debate regarding tints. For close up work where color matters (BBQ at night, wound inspection, or table light), the quality of light is so much more important than whether it's 5000K or 4000K IMHO. And accordingly, for throw, who needs high CRI light at 100m?

That being said, the Nichia 083 is as close to sunlight tint with High CRI that's currently out there, I think. Too bad it's output is so low.

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Tint only becomes an issue at the extremes. For me personally, if I'm under a light long enough, anything from about 3500K to 6500K will look "white". It's the extremes which are an issue. I have some of those high-CRI XPGs. While I agree the color rendering of warm colors is excellent, I find my eyes simply can't find a white point, no matter how long I'm under the light. I have the exact same problem under incandescent light. Everything looks like it's bathed in a yellow haze. Also, when tint is this warm, cooler colors just don't render well. It's hard to tell navy blue from black, for example. On the other side of the scale, very high CCTs just distort warm colors, not matter how good the CRI. And they always make white look blue.

In my opinion, both tint and CRI matter. CRI simply needs to be "good enough" for the task at hand. For non-critical general illumination I'd say mid to low 80s is good enough. For critical color matching applications, you might need 90 or better. For outdoor lighting, probably 65 to 70 is adequate. Once your CRI is good enough, then you need to find a tint which has a CCT in the middle of the extremes to which you can adjust. This is what I refer to as your "natural white point". I'm sure this varies somewhat from person to person. For me with extremes at 3500K and 6500K, my natural white point, the CCT under which my eyes are least stressed, would be around 5000K. This is actually my preference for the linear tubes I use.

In a nutshell then, that's why tint matters to me.

Thoughtful post.

I think you have it about right. I would PREFER to have a light around 5000K with a CRI of 95, with 300 lumens at 1.5A. That's for sure.

obi

Thanks for the posts!

It would be very interesting to see how does a 5000K normal LED and a 5000K High CRI compare