XP-G - why the doughnut hole?

[tre]

After the mention in the most hated and most loved emitter threads, I thought this issue deserved a thread.

Almost every light I own with a single XP-G emitter has bad doughnut hole to the point where I even notice it outdoors. I don't yet own a light with a triple or quad XP-G but I can see how this would be great because there would be no single emitter doughnut hole. So what is the issue? Some would argue poor reflector design, which may be quite valid, but there must be something about the XP-G that makes it very difficult to design a proper reflector for a single XP-G. It is the emitter or the reflector?

 

[csshih]

reflector.

odd. every single XPG light I own does not have a donut hole...

 

[ACRbling]

It's due to the wider angle in which the xpg projects the light. So far no one has made a smooth reflector which can eliminate this problem, that I know of.

One day...

 

[Kestrel]

Almost every light I own with a single XP-G emitter has bad doughnut hole to the point where I even notice it outdoors.

Out of curiosity, what lights do you have that are like this?

My guess would be that many manufacturers tried to get an XP-G in their lights as quick as possible by just doing an emitter swap into their existing light models. Has someone posted somewhere that the mounting PCB of the XP-G was of slightly different thickness than previous units from Cree, requiring a different mounting height for existing reflectors/optics ? :shrug:

The only single-emitter XP-G configuration I have is the Malkoff M31W, and it has the finest beam I have ever seen from a flashlight.

 

[Black Rose]

Has someone posted somewhere that the mounting PCB of the XP-G was of slightly different thickness than previous units from Cree, requiring a different mounting height for existing reflectors/optics ? :shrug:

Don't know if it's been mentioned, but I have purchased XP-G R4s and R5s already mounted on bases and the heights of the bases were different.

The height difference was not huge, but it made a big enough difference in beam quality that the higher height board is now in my parts bin.

 

[carrot]

Every XP-G light I have owned has had nothing short of a perfect artifact-free beam. I suspect the lights you have just have poorly designed reflectors? Or are optimized for throw, in which case the donut is considered a trade-off.

 

[ichoderso]

Hi, I own over ten XP-E and six XP-G lights but no single one with a donut hole
If i buildt my first XP-G light (modded an old XR-E dropin) I noticed that i get a donuthole, if the led is to wide inside of the reflector, take a small o-ring between reflector and LED ( or plasticfoil or wathever get more space between this two parts) and the hole will gone

Jens

 

[PCC]

I have about 8 XP-G lights. No donuts here.

 

[recDNA]

The only XP-G donut hole I've seen was in a Maelstrom. It's also the only smooth reflector XP-G I've owned.

 

[F250XLT]

Like others have said, it sounds like a problem with focus.

 

[tre]

Out of curiosity, what lights do you have that are like this?

Fenix LD40 and LD20, EagleTac T20C2 MKII, 4sevens Maelstrom G5, Zebralight SC60, Quark 123 regular, and a Dereelight Javelin are all lights that I currently own that have it (some much worse than others). There have been many other XP-G lights which I've sold that had the same issue.

It seems to be limited to the XP-G because I've not noticed this in any XR-E, XP-E, SSC P7, SSC P4, SST-50 or SST-90 lights I've owned.

I have an M31w on order so I hope it is as good as everyone says. That is about the 10th positive comment I've heard about this drop-in.

I will also be ordering the quad XP-G when the official sales thread is started.

 

[jellydonut]

Because manufacturers can't or won't focus it properly. There's nothing wrong with the emitter.. Of course it is easy to blame the emitter to sell shoddy lights.

My Malkoff Hound Dog, M61s and even my Malkoff XP-G 2C Mag dropin with the standard smooth Mag reflector all have perfect beams. The Mag dropin of course has a pencil hotspot when focused and isn't all that good for general purpose use, but no hole to speak of.

The Wildcat V2 I had and my current Oveready triple of course have perfect flood beams but multi-emitter lights don't really count, I think.

I guess it is worth to note that my two Zebralight H31s also have very nice flood beams, which one might not expect from that manufacturer.

 

[Jash]

I had an issue with an M61 and Gene said it wasn't the reflector but the XP-G led. Apparently the emitter will emit warmer light around the edge (or in the middle, can't remember which) and a cooler light in the rest of it. The warmer part of the light gets thrown into the middle of the hotspot and therefore looks like a donut, but it isn't, at least in the M61. I can live with it, it's not noticable outdoors.


My Quark Tactical has a flawless beam, my Quark Turbo has a donut. I think there are a few factors beyond the led that will determine the beam shape.

 

[offthetrail]

EagleTac T20C2 MKII

Which reflector do you have? I just got this light last week with the LOP reflector and there is no doughnut hole at all that I can tell?

Selfbuilt had the same results in his review. No doughnut hole with the LOP reflector, but there was one with the smooth reflector.

 

[tre]

Which reflector do you have? I just got this light last week with the LOP reflector and there is no doughnut hole at all that I can tell?

Selfbuilt had the same results in his review. No doughnut hole with the LOP reflector, but there was one with the smooth reflector.

I don't have the LOP - I have the SMO (I purschaed it when it first came out and at that point SMO was the default reflector).

 

[CarpentryHero]

My fenix PD30 is the only donut emitter, not much of a brightness difference between the center and the circle, maybe 5 to 10 lumen difference.
Its the smooth reflector. If it was orangepeel it'd be fine I think.

 

[shipwreck]

I don't have the LOP - I have the SMO (I purschaed it when it first came out and at that point SMO was the default reflector).

That is why.

I ordered a smooth reflector on the P20C2 Mk II, and the vendor I ordered from stated that they no longer carried that, due to all the donut whole complaints. He sent me a LOP one, and it is fantastic. My T20C2 Mk I also has an LOP reflector

 

[Notsure Fire]

I wouldn't understand why they'd make the hole if its detrimental to performance.

 

[jimmy1970]

My Quark Tactical has a flawless beam, my Quark Turbo has a donut. I think there are a few factors beyond the led that will determine the beam shape.

+1 - I think that just about sums it up.

James.....
www.CoolTorches.com

 

[SCEMan]

No doughnut holes with my XP-Gs

2 Quark 123-2s (OP) - Perfect beams
Solarforce P60 (SMO) - Perfect beam
Dereelight p60 (OP) - Perfect beam
G5 Maelstrom (SMO) - Ring-free but slightly darker center spot