CRI vs. alternatives with measurement examples

I have never done that so can’t promise anything. I would have to look up what’s required in terms of skills and equipment.

These are all just lights I have bought myself so the amount of data is naturally limited.

Wow. Amazing. Can you state what LED is in each light too? Great info.

Updated table with manufacturer info about emitters.

Thanks for the great quality posts. Looking forward to more.

Thanks, excellent article

Nice work!!!

Can I send you some stars with a LED on them?
Then all you need is a cell and two wires to light them up.

Sent a PM.

Nice work. I don’t claim to understand any of the test methodologies (or what goes on behind the numbers), but I am surprised that the average rating of all the test items correspond directly with their CRI (Ra) index. It seems like you could just do that one test and skip the rest.

I see what you say here, but there’s a few differences here and there. It tells you that CRI is is a working indicator for colour rendering. But it costs nothing extra to use an indicator that is even better, and it helps the industry setting the right target for the products instead of a slightly wrong target.

In general, when you start testing things you have not tested before, often after a while you see a pattern: already from initial observation you can predict how it most likely will test. From that moment on, the tests will be less informative, but if you stop actual testing you will also miss the surprises: occasions where specimens test very different from your prediction.

Nice
then I will send you
A Nichia 219C
A LatticeBright with not so bad color
A star with a 1w warm white led we have used in the kitchen and I wanna mod into a flashlight
All on stars no soldering needed.
Nice to have the 219C measured for a more complete overview.

Now wait when we are at it I will also send the XHP50 and XHP70.
Really appreciate that this is possible and you are sending them back afterwards.
Let’s build a comprehensive list right?

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.