LED test / review - Osram OSTAR KW CSLNM1.TG / KW CSLPM1.TG (≈ 6500 K, typ. 65 CRI)

Thank you. :)

For me the most important part is color and light quality. Efficient are almost all emitters, even in High CRI (except for some horrible inefficient emitters like the pre-production Getian tested several months earlier), and also the trend for many flashlight enthusiasts goes to light quality since more or less precise light measurement devices like the "Opple" are cheap and easy to use. Only through such equipment do most people even perceive the topic of light quality and effects on the human body. Before, terms such as Ra and duv were only theory for most, and now this topic can even be applied in daily life, for example in lighting for living spaces.

And yes, it is important for me to test many different emitters, from highest luminance to best color rendition and even pure exotic things like SFP55 and other obscure emitters.

I will search for the microscope luminance paper. It was a while ago, I don't even remember in which journal it was published...

It is very interesting to hear what your priorities are regarding emitters, given how many of them you have tested and are intimately familiar with. It is true that emitters are becoming extremely efficient, even the high CRI ones. (I actually don't know if they're even truly less efficient than their low CRI counterparts, since lumen/W measures efficacy, not efficiency...but that's a whole other discussion that I am more than happy to go in more depth.) I think many efficiency problems in flashlights can be attributed to the driver and optical element, more than the emitter.

Nowadays I require all emitters I have to be top-performers in at least one department, and as a result, the only white emitters I use are the 519A, CSLNM1, and SFT40. (I don't use any big lights but would have liked the 50/70.3 HI.) Many common emitters (e.g., SST40, LH351D), for me, are strictly inferior to another emitter in every department and thus have no place in my collection. For my EDC I care most about color quality. After a few months, I actually got tired of how pink the dedomed 519As are, and ordered some domed ones to put back in. Facepalm.

My other main is a C8 running SFT40, which for me is the emitter that perfectly compromises between throw, output, and efficiency/runtime. The SFT40 is crazy efficient despite being a high intensity emitter and has excellent tint given the low CRI. An argument can be made for the CULPM, but the SFT40 is so much easier to center and more mechanically robust.

This is a point of confusion for me.

The LES size matters if you’re measuring total amount of light put out by the LED, you divide the total brightness by the LES size to get average intensity. But the only way i know to do this would be in a lightbox (even if you’re using your room as a lightbox) and it is the LES size that matters, not the reflected LES size.

If you’re using a light meter to measure the LUX of the brightest part of the hotspot at 1m then you are already measuring intensity, the only other factor you need is the distance at which you are measuring, you don’t need LES size.

And if there was a reason to need the reflected LES size that i don’t know about, the reflected LES size would be the same for all LEDs once you get past the distance at which the beam is fully collimated (which is the point here) as it would be limited by the size of the reflector.

What’s your process for determining luminance?

I compared brightness in 1 and 4 m distances.

In 4 m distance,for a domed XP-G2 S4 (new design) I measured 4 percent higher brightness. On the other hand, with a CSLPM1.TG the brightness in 4 m distances is lower, with about 1 percent lower. I can't figure out why there are small differences, and I just realize that measuring brightness and therefore luminance is much more difficult if precise values are desired. Maybe it is because of the viewing angle and the dome on the emitters, I don't know.

Wow, I don't really know how to make sense out of that result either. I would expect different behavior between domed and domeless emitters due to differences in angular distribution, but am very surprised to learn that the CSLPM measures lower at 4m.

Sometimes, depending on how it's focused, a reflector can produce an abnormally intense and very small hotspot within the normal hotspot at around 1m distance. If you bring the light to the wall, you see a vaguely cross-shaped hole in the center of the beam. As you move the light back, the hole gradually fills in, and there is a point where the center of the hotspot flips from being dimmer to being brighter compared to the rest of the hotspot. For my C8, this happens at close to 1m, and is my only possible explanation for what's happening.

Hi koef3,
any chance you did a review for some of these LEDs:
Osram KY CSLNM1.FY - orange 590nm
Osram KR CSLNM1.23 - red 612-616nm
Osram KP CSLPM1.F1 - green (unknown wavelenght) and
Luminus SST-20-DR-B120H - deep red 660nm

I think have the Luminus SST-20-DR-B120H at stock, but older samples from 2016-2018.

I don't have currently planned to test the other mentioned emitters, since I would have to buy these LEDs specifically for the test, with no other use for these emitters. (I am not really interested in flashlights with color LEDs.)

How much time does it take to make a review for one LED?
If you are interested I might be able to send you some samples for review!

It depends on the scope of the test and if I put all types/colors in one test.

The problem is that I have to calibrate my new integrating sphere with a reference light source. I do not know exactly when this will be the case. For colors I have to calibrate the sphere with colored LEDs with known binnings, which will take some time. Overall I think half a day will be sufficient.

You are welcome to send me samples but I don't know exactly when I will get around to testing them because of the reasons I just mentioned.

Nice test koef3!

“I would assume that the old well known dedomed XP-G2 S4 2B is no longer necessary since this LEDs offers higher luminance without the need of changing the emitter mechanically beforehand and at a much lower forward voltage.”

I think I am probably one of 0.01% of people who still uses, and still have them stocked since I took almost all batch from IO store when they appeared. Mentioned dedomed Cree Emitter should not be underestimated even in these days of high intensity emitters even in direct comparison with this newer White Flat emitters! Yes they will throw more but let’s say CSLNM1.TG will have less lumens for just up to 15% better throw performance(which also depends because I had some crazy XP-G2 S4 2B emitters in almost same range as M1.TG and now if I compare it to KW CSLPM1.TG? Well it depends… “Greenish” tint of dedomed S4 2B is something that my costumers(hunters) actually prefers over cold white tints :smiley:

But It is no “longer necessary” is also correct, and probably there are only very few of those “Dinosaur era” emitters remaining on the planet. So why look back? Still waiting for China round emitter test :wink:

See you!