High CRI, question about possible solution?

[Ventzy]

My expierence, is that high CRI, usually is much more important than lumens. As I see, it is very difficult to find LED's, with high CRI on the market, and of course LED technology itself, have some limitation to have good full spectrum radiation. OK, is somebody know why, for example, LED's like MCE (4x), are not produced with four different tint inside. Then in final output, will be much more wide and equal spectrum?

P.S. sorry for my english, it is not my best...

 

[Paul_in_Maryland]

FourSevens' Quark RGB uses an MC-E with 4 colors. The MC-E allows all 4 colors to be "on" at the same time, but the Quark RGB uses only one color at a time.

I have a different idea: Why can't Flashlightlens.com sell lenses that compensate for various tints?

 

[Moonshadow]

Interesting suggestions, Paul, but unfortunately it's not quite that easy.

Blending with the MC-E sounds tempting, but each of the coloured segments (red, green and blue) emits only over a narrow range of wavelengths (10-20nm or so), so you'd get a spectrum with three spikes in it rather than the broadband spectrum that you need for good colour recognition.

The trouble with filters is that they can only subtract light, whereas what you really want to do is to convert more of the blue light to longer wavelengths. So a cool LED with a filter in front of it would be even less efficient than a warm emitter.

 

[fyrstormer]

Cree does do this, though it's not intended for focused applications: http://www.cree.com/products/xlamp_mpl.asp

 

[Paul_in_Maryland]

The trouble with filters is that they can only subtract light, whereas what you really want to do is to convert more of the blue light to longer wavelengths. So a cool LED with a filter in front of it would be even less efficient than a warm emitter.

I know, but isn't that how all LEDs are made white in the first place--by filtering out the blue? Aand arren't warm white LEDs made by filtering out more blue?

 

[AnAppleSnail]

I know, but isn't that how all LEDs are made white in the first place--by filtering out the blue? Aand arren't warm white LEDs made by filtering out more blue?

No. A yellow phosphor glows yellow when energized by light. Blue light is used for that, but the phosphor emits its own light.

If you filter light, you only remove light - you can't get blue from yellow. White LEDs use physics to change blue light into yellow light, and warm white ones do it to more of the blue.

 

[qwertyydude]

White led's do not filter out blue. What they have is a set of phosphors that convert a portion of blue light to red and a phosphor to green. They have to balance the mix to get white since red+green+blue=white, to get warm colors more more red is added. But the more phosphors you add the less overall light gets through. This is why cooler lights tend to be brighter. High cri lights use special phosphors that cover more of the light spectrum.

 

[flatline]

I know, but isn't that how all LEDs are made white in the first place--by filtering out the blue? Aand arren't warm white LEDs made by filtering out more blue?

No, it's my understanding that phosphors are added that absorb some of the EM from the LED and re-radiate in a different frequency. The tint of a power LED is determined by the the types and amounts of phosphors selected.

--flatline

 

[Tally-ho]

Cool and Warm white conversion (our flashlights use the second method):

White light is achieved in three different ways. The first method is color mixing, using individual LED colors: blue and yellow to create a dichromatic white source; red, blue and green LEDs to create a trichromatic white source and blue cyan, green and red LEDs create a tetrachromatic white source.

A second method is binary complementary wavelength conversion. A blue LED is complemented with a yellow phosphor to create cool white light with a typical color temperature of 5,500K. By adding a secondary red phosphor, a warm white color with a color temperature of 3,200K is achieved.

The third method is ultraviolet wavelength conversion, in which a single ultraviolet LED is used to excite a tri-color phosphor coating, which in turn produces visible "white" light.

Source: http://forum.lowyat.net/index.php?showtopic=1252081&st=600&p=30953905&#entry30953905

 

[GunnarGG]

The neutral whites look better to me than the cool white do but if I point one neutral and one cool white on the same target it gets (or at least looks like) better CRI. If I then also add a warm white it gets even better.
So a light like Eagletac M3C4 with 3 LEDs in warm, neutral and cool white would make a great tint and show colours well.

 

[Ventzy]

The neutral whites look better to me than the cool white do but if I point one neutral and one cool white on the same target it gets (or at least looks like) better CRI. If I then also add a warm white it gets even better.
So a light like Eagletac M3C4 with 3 LEDs in warm, neutral and cool white would make a great tint and show colours well.

This is exactly my idea. MC-E have four independant LED. If they are different tint, may be final result will be much better CRI... I am also made test with two flashlight (neutral and cool white) together in one point... it is much better...

 

[Belstaff1464]

Please ignore my newbie ignorance, but why would you want to go down this road when there are high CRI LEDs available, eg HDS Clicky/Twisty, McGizmo, etc ?? I believe there are modders that do swap cool emitters with high CRI LEDs. Am I missing something here ?

 

[Ventzy]

As I know, there is very big problem with LED with high CRI... Very few manifacturers have production with high CRI. And none of them have something with high output like JetBeam M1X for example...

 

[DaveTheDude]

The neutral whites look better to me than the cool white do but if I point one neutral and one cool white on the same target it gets (or at least looks like) better CRI. If I then also add a warm white it gets even better.
So a light like Eagletac M3C4 with 3 LEDs in warm, neutral and cool white would make a great tint and show colours well.

Hi guys. My suggestion is to have Nailbender make you a "Linger Special," which uses two emitters placed into a single P60-style drop in. Specify one of the emitters as a 4400K LED, and the second emitter as a 5700K or 6500K LED. This way you get a torch that produces a broad spectrum of mixed light, with the dominant frequencies far enough apart to emphasize both the "warner" and "cooler" parts of the spectrum, but still close enough to qualify as "white" light. Your eye will blend the light from the two emitters. Because the range of the spectrum emitted from a torch using two emitters as described in this post is broader than a single-die light, you will perceive the images reflected back to you from the objects you are viewing as more balanced, broad spectrum light, and thus appearing more natural, like in sunlight.

Here's a quick test you can perform to see if you might like this kind of light setup: take one warm white emitter, and one cool white emitter of approximately the same output, and shine them onto the a multi-colored object or scene. Alternate between the warm light and the cool light, then shine both onto the object at the same time. I suspect you'll quickly see (and understand) whether this kind of setup would work for you. lovecpf

 

[GunnarGG]

Please ignore my newbie ignorance, but why would you want to go down this road when there are high CRI LEDs available, eg HDS Clicky/Twisty, McGizmo, etc ?? I believe there are modders that do swap cool emitters with high CRI LEDs. Am I missing something here ?

I have thought about buying the HDS clicky high CRI but i'm hesitating because:
1: I don't need another light
2: It's expensive
3: I don't know if I will be satisfied with the total output (probably enough).
4: I don't know if the high CRI is that much better than neutral white that works fine for me most times.

The big question for me is then: How much better is it compared to an ordinary neutral white light? Is it as good as my example above in post #10 when warm, neutral and cool is pointed at one spot?

That M3C4 with mixed tints would make a great light, don't you think?

 

[flatline]

The big question for me is then: How much better is it compared to an ordinary neutral white light? Is it as good as my example above in post #10 when warm, neutral and cool is pointed at one spot?

Okay, here are the subjective results of lighting my bookshelf in a dark room with various lights.

High CRI Ra Clicky: all the different colored bindings look great

5C tint: some colors look decent, others look washed out. this was my favorite tint before getting the high CRI Ra clicky.

5C + 5A: slightly better than 5C by itself, purples and reds look better.

5C + 5A + WC: fair improvement over the neutrals. purple actually looks pretty good.

5C + 5A + WC + 7C: most colors look pretty good. Different shades of the same color aren't as noticeable as with the high CRI, but the differences are getting subtle enough that you probably wouldn't care about it in actual use. It's possible the differences at this point have more to do with color temp than CRI.

Of course, this is all subjective. Clearly, combining the tints is a huge improvement over any of the tints by themselves, but with the tints available to me, I couldn't get a result as pleasing as the high CRI emitter by itself.

--flatline

 

[Ken_McE]

My expierence, is that high CRI, usually is much more important than lumens.

At this time, if you need the highest possible CRI, you should look at incandescent lights.

P.S. sorry for my english, it is not my best...

Your English is fine. Don't worry about it.

See also:

http://www.candlepowerforums.com/vb/showthread.php?t=292941

 

[GunnarGG]

Of course, this is all subjective. Clearly, combining the tints is a huge improvement over any of the tints by themselves, but with the tints available to me, I couldn't get a result as pleasing as the high CRI emitter by itself.

This sounds bad, I don't know for how long I can resist that high CRI HDS clicky...