Donut hole in my new Fenix TK20

I recently acquired a fenix TK20. But I noticed a donut hole in the light. It reminds me of the old Lux V LED that was notorious for having that problem. Is what I seeing just a cree ring? I have heard that term mentioned mentioned but I have never had it explained. When I tried searching for it all I came up with was people describing if a light had a cree ring, not what it was.

The very middle of the hotspot is darker than the outer part. I have not heard of this before, but it is one of my first lights with a new cree LED. So am I just imagining it? Or has others had this same problem? It is not that noticable in the real world, but it is fairly noticable if I use it in the house.

Thanks for your replies.

Yes, my TK20 has it too. It doesnt really bother me since I don't point it to a while wall anymore :lolsign: i can't really use the tk20 indoors so I sometimes put a thin scotch tape to smooth the beam out.

1anrm said:

Yes, my TK20 has it too. It doesnt really bother me since I don't point it to a while wall anymore :lolsign: i can't really use the tk20 indoors.

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mine has the hole too. i could get by with it on low indoors but i actually use it more during the day indoors on high. this is one case where i don't mind a cree ring at all. :twothumbs

Neither of my TK20's have a hole like what your referring to.

The second TK20 was more ringy than the first, but there was no dull spot in the hot spot.

My LD01 SS does have a slight dull spot in it, but its only noticeable if i'm pointing it at a wall and i'm looking for it.

Ok, thanks for the replies. I am just making sure I am not the only one. I think once I get it into a cave and camping and such I won't mind it at all.

G'day fella's.

I'm new here though I've been reading hundreds of posts over the last three weeks.

I received my new TK20 torch in the mail today. I was hugely disappointed when I turned it on to find a very dark shadow in the centre of the hotspot (the hotspot seemed more of a dark spot with a very bright ring around it).

That dark centre was there on a wall from five yards away, it was there on a wall from twenty yards away. I went searching for "TK20 donut" on here and found this thread which made me feel a little better in that it seems a common situation for these lights.

Years ago I'd experienced a dark centre on an old maglite when I moved it slightly off sharp focus which got me thinking and I came up with a mad plan. Here's what I did:

I took the head off the TK20 and used two pairs of multigrips (with rubber between jaws and light) to unscrew the "end" of the head from its base thinking this might change the "focus". I only turned it about a six of a turn but it worked. The dark centrespot was totally gone, replaced by a bright centred hotspot as it should be. My torch has gone from a huge disappointment to something I know I'm going to love and cherish.

The reason for two pairs of multigrips was that the threads appear to have been "loctited" so needed great force to unscrew. Having unly unscrewed it slightly there's still no looseness of lens etc and the loctite is still holding very tight too (it still won't move further without multigrips).

I am aware I've probably voided my warranty but it's an ebay buy out of Honkers and I'm not a warranty type bloke anyway. By the time shipping O/S etc is paid I find it's often just better to buy a new torch.

Anyway, I post this (as my first post) in the hope that it may help someone who has received a dark centred TK20 and hates it but just can't bear to send it back.

Regards,
Dave.

My 1st TK20 has no donut, but I just bought a spare that has a little shade in the middle of the hotspot.
I dont think I will notice it when using it outside, it can only be seen on a white wall.

Maybe ill try loosening it a bit :thumbsup:

And welcome to CPF :wave:

I'm new here... am considering a TK20 to add to the few I currently have on order, so finding this was great! Thanks for the tip Dave! :thumbsup:
I've been reading here for a few weeks now... amazing information and from what I've seen, an amazing group of people. I'm looking forward to learning and hopefully contributing in any way I can!
- Tim

Mine has a major donut hole too... I guess it´s because the smooth reflector.

Anyway, I only see it while white wall hunting. In real use, in real world, I can´t see it, and it doesn´t bother me at all...

I never noticed a dark hole on any TK20 and I've got two of them (one for my wife) and checked 4. Believe me that I checked thoroughly, as two of them were to be given away, I needed to find the two best ones...

I got the first ones when they came out and the last ones about half a year ago, they were of different series, as two have the yellow base under the LED dome, two the silver one, the beams seemed all more or less the same.

I guess the really new ones have a problem, bad QC perhaps? :candle:

I think my one was a QC problem. The problem was much much worse than any of the ones I've seen in beamshots on here. The beam really just looked like a very bright ring rather than a hotspot. I thought that like otehrs here I would maybe not notice it in outside use but it was actually so bad that when I used using the torch on outdoor objects even fifty yards away I was finding the dark centre such a distraction that I found myself moving the torch beam off centre to bring one side the bright ring onto the subject. If my mad plan handn't worked I'd have never used the torch. It works great now though.

The tint is definately a sort of yellowish to my eyes when I use it outside at night and I can take it or leave that colour for night time long raneg work as I don't have any trouble picking things out at long range in the bush with the cool tints of say my Led Lenser P7 but one area where the TK20 tint does really seem to standout is in daytime work.

Yesterday I had cause to search a large and cluttered storehouse looking for a snake (Eastern Brown, very deadly). The strorehouse had white walls and was filled with lots of ambient daylight and my fenix L1D on turbo wasn't cutting it when trying to shine through gaps between objects on shelves etc. Not so much that it wasn't bright enough but because the cool white tint of its light seemed to be blending into the daylight. I changed over to the TK20 and the yellowish tint made it very easy to cut through all that white. The narrow more defined beam also helped in "poking the beam" into small gaps.

Definately a very good practical torch.

I've had mine now for just over 2 weeks and I have been using it outside when walking my dog. I never noticed any problem in the hot spot...it just throws far with a nice color. So tonight I did a white wall test...Yes, the center has a little more "tint" than the outer edge of the spot. I wish all my lights were like this. Maybe some are darker than others? I sure am happy with mine. Just my 2 cents...

Ok reading all this made me crack out mine. Maybe if I look at the white wall for a few minutes there could be somekinda very small darker spot in the center if I use the light at say 12 feet or more but it is hard to tell even on a white wall and impossible to see in the woods. Sorry to hear about these issues just the same. There is some beam shots posted on a TK20 thread I did sometime back

https://www.candlepowerforums.com/threads/231371&highlight=tk20+dreams&page=2

Since I prefer flood, I recently bought a TK20 with a Olilight M20 push-on diffuser (about $12 shipped). The diffuser is a bit too wide in diameter; I could make the fit snug by wrapping the TK20's bezel with two or three layers of electrical tape, but then the bezel wouldn't fit the TK cone diffuser and traffic wand.

As you would imagine, the M20 diffuser completely changes the TK20's beam shape into a v-e-r-y wide circle that looks much dimmer. Because the TK20 is a thrower, most of it passes through the center, so there's still a pronounced hotspot.

I'm not sure I'll keep the M20 diffuser in place; it takes a great thrower and turns it into a so-so flood. A better solution would be a flip-up diffuser, like two of the Surefires. Fenix offers one for their 21mm bezels, but not for the much wider TK bezels.

offroadcmpr said:

But I noticed a donut hole in the light.

The very middle of the hotspot is darker than the outer part.

Click to expand...

I bought 3 TK-20's and all had both of the items you describe. I was not happy with the brightness of them, but the items you descibe didn't bother me. Mardukes pictures of the abuse he puts his TK-20 through has given me enough respect for the light that I take it hunting with me. It's bright enough for following a path, and I love carrying just AA spares into the field for everything including my GPS.

I believe the darker hot spot surrrounded by a ring of brighter light is because of the smooth reflector. I have had three lights with this phenomenon, but it disappeared after I changed the reflector to an orange peel type.

Enjoy your light. It's fine.

Bill

I passed on buying one today because of the donut in the beam. Its not a major problem, but it didn't exist in the TA30, which is pretty high on my list of lights to buy.

My Pd30+ R2 suffers from the doughnut hole, this is my 7th Fenix (PD20, P3D,L0D ,TK11 q5,P1D and LD10 clip) and fortunately the only one with the hole but is also one of the newest designed

Sorry for taking things slightly off-topic,but does the Fenix TK40 suffer from the same donut-hole effect?

How bad is this donut hole? In my previous post I explained that I did not know it was even there until a white wall test. Even then it takes "trained flashohalic eyes" to see it. You can't see it outside at night in the real world. It is not like a Mag adjusted to flood with a 3 foot black voided dark spot. Watch where you step with that setting!
Are some TK20's worse that others? I'm so happy with mine, I can't recommend it enough.

what OP posted is simply a "misaligned" reflector - for his needs.
Open light, put thin sheet of non conducting material between reflector and where it sits, reassemble and check.
When lucky the reflector was too deep and that problem is solved,
if not lucky the reflector was too high originally, then remove the material.


A "Cree Ring" is a single gold colored "ring" in the middle of the spill part of the beam, coming from reflections of the XR-E metal ring inside not too good reflectors (these are reflectors, where You can see an image of the metal ring in the reflector surface).
And only possible with XR-E model (inside not too good reflector).
So it is not "the cree rings", it is "the Cree ring":
main beam, spill beam with the same brightness all over, and the additional golden "Cree ring" in the middle of the spill part
--> seaming to make:
main beam, less bright beam part, bright golden ring, remaining spill

here, my best shot of a cree ring:


When there are several "rings", then the reflector is crap.