Beam quality or what would you like to see changed?

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Last seen: 5 months 1 week ago
Joined: 05/07/2010 - 20:42
Posts: 2571
Location: Seattle,WA
Beam quality or what would you like to see changed?

Beam quality can mean different things to different people I suppose. The one thing that it's hard to do much about that I would like to do something about is the look of the beam. A diffuser over the beam results in nice uniform light and I have no problem with that if I don't want to illuminate anything more than 10 feet away.

If extreme throw is needed or wanted in a certain situation I'm happy with the beam of most lights that are capable of that kind of throw primarily because at a certain distance you don't notice anything other than the center of the beam.

What I find most distracting if that hard outer edge of the spill when it goes from spill to abrupt darkness. It's nice if you have a reflector that has a softer edge to the hotspot so that transition from hotspot to spill is smooth but it's the other edge of the spill that's more annoying.

The best way to reduce that is to just reduce the spill with a collimating lens as happens in TIR optics. You don't usually notice that hard edge with a TIR when you are waving your flashlight around pointing it at something at night. With anything else when you do that you are distracted by that large "halo" moving around close to you as you are trying to focus on the subject.

That solution would be the "reduce spill" approach. An aspheric would be the block spill approach as would a cylinder attached to the head.

It would be nice to find a way to diffuse the area near the edge as you go from spill to abrupt cutoff. Given the way reflectors work that would be hard. At least I haven't been able to do it yet.

I don't hear this talked about very I the only one that this bothers?

It's better in a XP-G only because the hotspot is larger and the spill is a little less intense but with my XP-G on high at night it's still very obvious as the spill cuts off to darkness.

You would think that you could stick a piece of diffusing film in the form of a small circle in the center of your glass lens since spill is the result of that light exiting the emitter than doesn't hit the reflector. You wouldn't effect the hotspot as that comes from the edges of the reflector.

I've tried this and it doesn't effect the hotspot but as far as I can tell it doesn't really effect the spill intensity much either.

Anyone else think about these things or have any solutions? I'm more interested in improvements in beam quality that lumen output once you reach the XP-G level and above.

brted's picture
Last seen: 3 months 2 weeks ago
Joined: 01/12/2010 - 19:44
Posts: 2371
Location: Atlanta

I like the whole idea of a hotspot and some pretty decent spill (I don't mind an abrupt cutoff from spill to nothing). I can see where just a hotspot would be useful if you were looking at things far away, but generally I want both. And I don't like all flood like you would get with a diffuser. I want some intensity to the beam, not just a light bulb. Indoors it is easy enough to bounce the light off the ceiling and get a pretty uniform light if that's what is called for.

By good beam quality I think people are looking for an intense hotspot with a decent transition to spill. The Cree XR-E in particular seems to always have a dark ring around the hotspot. And the multi-die emitters have a dark spot in the center which is kind of annoying too. Outdoors when you are moving the light around anyway, these don't matter as much. My P60 XR-E is about as tight a hotspot as I would want, so I find the XP-G's to give a better pattern. But in AA or AAA size lights, the XR-E's work pretty well and give decent throw with a smaller reflector.

alfreddajero's picture
Last seen: 10 months 6 days ago
Joined: 01/14/2010 - 00:28
Posts: 1798
Location: Virginia Beach VA

As Don said in a previous post especially with the L2's i noticed that if i take the small attack bezel off i get more spill......When i first got into Cree Emitters one just gets used to the rings its to the point now that it doesnt even matter to me.  I do notice that with Luxeons the beam profile is just smoother then with Cree's.  I cant rant because if i  do that then i would not be in this hobby at all.

With Darkness, there will always be Light.



Don's picture
Last seen: 9 months 1 week ago
Joined: 01/12/2010 - 16:32
Posts: 6617
Location: Scotland

Surefire's incandescent dropins have very, very narrow beams compared to just about anything - one of the reasons they seem brighter than you'd expect for the lumen rating is that just about all of it is in a very tight hotspot. So bezels designed round that don't work so well with the generally wider beams of LEDs.


The numbers from my light tests are always to be found here.