CRI vs. alternatives with measurement examples

Every individual emitter will test a bit different, so there will not be ultimate results. You could detect false claims by sellers though.

Another (uknown) factor is the applied reflector. The reflector will only direct a part of the light rays into the hot spot. The direct (bluish) rays Will miss the reflector and go into the spill. A measurement of the LED without some (standard?) reflector can give misleading results.

Fascinating. I’d be interested to see the values for a regular neutral-white XML2 when you test one, since it’s used on so many of my lights.

R (9) looks so bad on all those lights, with the exception of the Nichia 219B. What kind of Nichia 219 5000K emitter gives the bad R (9) value? Is that just because it’s a bit cooler, and so there’s less red in its spectrum, or is it a 219C that is generally less good at red?

What does a negative R (9) value actually mean?

Well testing some will give more data then testing none :wink:
Maybe each emitter is slightly different, but there must be enough similarities in tint that is close enough in the same bin, otherwise all reviews of leds have little use right?
For weight sake I will not send the S70 (also removing that is more difficult then the easy to access S50 XHP50) and for my eyes the tint of the two is similar, of exactly the same.

Here are the results for the bare unspecified emitters The Miller sent me. I was surprised how cool white the XHP50 and Latticebright turned out to be without a reflector.

I didn’t have any specs for the emitters so the voltage and current weren’t set for maximum brightness, because I didn’t want to destroy them and there was no cooling except for the stars. I did test them on different output levels and didn’t notice significant change in CRI or tint after reaching a certain threshold of usable output. The XHP50 was run at 6 volts and 1,5 amp and it was blinding.

Nice!
Thanks
I will certainly use that household spot led

That LB is not so bad (cursing in the church here, but some of the LB emitters do produce a nice tint (sorry sorry but they do))

Here’s the newest color rendering method, IES TM-30-15 (lots of interesting information in the pdf), which is supposed to be much more reliable when measuring leds. The basic workings are similar to the original CIE CRI but with several improvements. I’ll include most of the metrics specified in the method in my future tests.

That was a good read! The method provides a CRI-like general colour rendering qualification, as well as a wealth of more specific data about a given light source that is really helpful for general lighting applications, but may be a little overkill for a mere flashlight :wink: . But that never stopped us from wanting it anyway :slight_smile:

Thanks for another interesting thread.

Great! I'll take a good glance at the IES TM-30-15 document later (an amazing improvement it seems).

I always wondered how much emphasis did the CRI(Ra) standard set on violets, seems to me typical white led light sources may suck a bit in this regard.

Cheers ^:)

Great work. Which metric is best, in your opinion?

My gut tells me gai+cri for best vividness and naturalness. . I am suspecting/hopeing that cqs is better in this respect. I believe it was proven that people can’t remember color. I prove this daily, watching people get confused by shades seen a mere minute ago. So, puzzled at the memory cri metric.

Spectrograms of LEDs look quite disheartening…

Just read the tm-30-15 specs. . This is the holy grail. http://yujiintl.com/tm-30-15-high-fidelity-full-color-gamut-led-lighting

LED magazine had good article.

The CIE had better adopt this tm-30 standard! This is what I am after. If I only shot photos, I might not care. But, I use lights with my eyes to hunt subtle hue shifts.

Make your own spectrometer, from stuff you got at home. Led looks identical to the eye as an Incan or sun. You need special equipment to cut out the bottom 80 percent of illumination and make a graph. . I have seen led graphs that match the sun, close enough. Also, surprised, even the choppy CFL, does well in a 140 hue chart discrimination battle. Rbg led lights have the oddest graph, yet best for store fronts.

This tm-30 standard is what we need. Too bad engineers love numeric naming and it wasn’t called the 99 luft balloon proposal.

http://www.cie.co.at/index.php?i_ca_id=981

I am trying to research the 2017 status of the tm-30 It appears supported, but voluntary. Mandatory, only after everyone volunteers.

Am I getting right pulse?

all spectral images thanks to maukka’s posts:

N219b:

Nichia 219B-V1:

XPL:

CW XM-L2:

TiTool

CuTool

A wealth of information with real life examples about color rendering and the TM30-15 and how the average index is not often very useful, be it CRI (Ra) or TM30(Rf).

That was a weird class by Indonesian standard. They were eating… :laughing:
Very nice video Mauri!

- Clemence

Yes, I’ve noticed that many high-CRI lighting (whether it’s CFL or LED bulbs), make people look sickly, and food unappetizing. The holes and spikes in the spectrum make some things look unnatural, even though it might pass a CRI test well.

Some LED lighting is pretty good, though.

I think the CRI standard needs to be modernized.

Nice, apparently I could use my 7 year old i1 displaypro to test leds with this…. if I could justify the $125 software price :frowning:

Just remember that Argyll/CT&A requires a spectrophotometer (i1pro, i1basic pro/i1pro 2, i1 pro 3, i1Studio, ColorMunki) for the CRI measurements to work. The i1 Display and i1 Display Pro will only report the xy coordinates (CCT, duv).

See more in this thread: Approximating color temperature with smart phones and camera