Light loss in a S2+ triple mod, added similar data for a reflector light in post#8, added data in post#20

I made a mistake, just edited the beamshot in post#20

Yes. Of coarse we will have light loss through our triple optics. You will have light loss with single emitter reflectors too. There will always be light loss of some sort. Trying to keep photons all rounded up is like herding cats.

Are triples worth it. Let’s compare the same light with single emitter with reflector against a triple optic.

I think it’s more what you want the light to do.

  • If want a “pocket rocket” with maximum possible lumens to illuminate a wide area at close range - it’s hard to beat a triple or quad. For the same size light they simply emit more light more efficiently than you can get with a single emitter. They make an excellent choice for an EDC light where you mostly want to illuminate things in a room or your yard. For instance, if you’re trying to vacuum the floor, it is handy to have a light that lights up the entire floor in front of you. A light that most just lights up one spot is less useful.
  • on the other hand if you want a light that can illuminate something a hundred yards away, as well as being useful up close, then a single emitter can be much superior. Overall lumen output may be much less, but you make up for this with a much more intense hotspot.

From Djozz’s testing it sounds like a well-built single-emitter light may have around 15% light loss into the reflector and lens compared to maybe 20% loss into the bezel and optic of a no-lens triple. In my opinion, that 5% difference in efficiency isn’t enough to make a significant contrast between the two types of lights.

It will ultimately still come down to mid-lumen throw vs high-lumen flood. But as usual, it’s been a pleasure experimenting for the sake of knowledge. Thanks Djozz!

Yeah, especially when it’s completely overshadowed by three times the emitter lumens.

This test is very interesting but let’s not forget about efficiency gain with lower currents with multiple LEDs. According to data from Cree PCT:
Single XP-L HD V6 driven around 10W with Tj=60C (attainable with copper DTP) produces 1165 lm (@10.174W to be precise).
Triple XP-L HD V6 driven at 9.94W produce 1583 lm at the same Tj. Quad XP-L HD V6 driven at 10.01W will output 1681 lm.
That’s around 36% more for triple and 44% for quad. Higher efficiency means less heat and I assume here exactly same junction temps. So even if TIR waste most of this there’s still plenty of gain over single LED with reflector. As to perceived more heat for triples it also can be explained with the LED count - three LEDs have 3 times the contact area so will be more efficient with heat transfer to the radiator so it will heat up faster. This also means LEDs could run slightly cooler compared to single LED so will gain still a few percent of efficiency. If there’s a good cooling all of the above should be quite true and the difference towards multiple LED setup could be even higher. But there’s too many dependent variables to accurately predict in specific case, and with small hosts heat sinking may not be adequate. Someone with required equipment at his disposal would have to test that.

I LOVE THIS FORUM.

Just when I think I have an understanding of the variables at work, more information is shared by another member from another part of our planet, that sheds more light (pun intended).

Awesome!

Good point. Assuming your light is driven at the same current and is using the same type of emitter, a multi-emitter light should always be more efficient than the single emitter. This is because LEDs are inherently more efficient at low currents.

I think the issue with heat and multi-emitter lights only comes up when they’re heavily driven. You can’t drive a single XPL or Nichia 219C light at 15 amps… the LED simply isn’t capable of pulling that much current. But you can drive a triple or quad at those currents.

A nice set of tests, Djozz. Altonx has a point, a more complete picture might be had from finding what drive current it takes to generate the same OTF lumens from various set ups.

Also, polycarbonate is tough stuff but my main concern is that many optics, especially multi-die optics aren’t smooth like a lens but have hollows or other cast shapes that catch debris and are hard to clean. I still use them though.

Try the Carclo 10511 optic. Polish the front of it with jeweler’s rouge to remove the frosting. Gives a very pleasant beam pattern closer to that of a traditional reflector light … and unlike the 10507 there are no nooks and crannies for lint to build up in.

Thanks djozz!

I believed this to be the case with these triple/quad optics and dedomed/exotic emitters. I used to think even with the ideal LED the efficiency would be exactly similar to an average reflector.

I once built my BLF X6 into the copper 35mm triple (DD XPL) using the Cute-3 optic… Until I turned the light on without the bezel installed. What I saw was an estimated 1/4th of the light spewing out from behind the optic. It soon got modified into a triple reflector setup. I didn’t take any measurements but I’ll say the output went from disappointing to just about right. I used ET D25A reflectors from KD and filed just the lips of the reflectors so they centered perfectly on the MCPCB. There’s no bezel overlap either :+1:

Glad you reminded me. I’ve been meaning to do that.
I used to assume that the 10511 was just a 10507 with frosting until comfychair set me straight. Back when Noctigon released the first ever DTP triple board and triple mania began, quite a few people were polishing the Carlco 10511 optics.

+1

Thank you djozz for another great thought-provoking contribution. :slight_smile:

Interesting read.

ever thought of painting the id of the head white?

You can do that and a bit more light will come out, but the contribution to the beam in forward direction will be minimal, it will be light in random direction and possibly not even uniform. In close-up illumination it will certainly add a bit though.

thats the idea i had.
unsure whether the otherwise absorbed light reflected back to the side of tir could end up in the main beam.

What is “id of the head”?

Hi Djozz, thanks for the test. I always wanted to do the same test too.
FYI, big portion of the losses come from the leaked light at the optic aperture. Carclo make optics to fit major brands so they have to make sure none of them squeezed by lack of clearance.
I will replicate your test with the recessed leg’s holes to bring the clearance to minimum.

- Clemence

Bring it on! :slight_smile:

Thank you @djozz and others! Great data and fantastic analysis.