Surefire U2 question...

ZTGuy

Newly Enlightened
Joined
Jul 21, 2008
Messages
4
Hello everyone....been lurking here for a while, and finally decided to join and ask a question. I acquired a SF U2 about a year/year-and-a-half ago, and since then, read many things about the donut hole problem. I have a few other SFs that I use MUCH more frequently, like two Z2 Combat Lights, and an A2 Aviator. Now personally, I don't notice much of a difference, except when doing a thing who's term I learned here....."white wall hunting". My question to the FAR more experienced and informed members of CPF is this: Is the minor donut hole (mine is REAL minor) issue on the SF U2 really something that absolutely needs addressing/rectifying??? Or is it only an issue for the "white wall hunter", and really, for any and all intents and purposes, does not make the slightest lick of difference when employed in the field. Again, I'm gonna contend that, for practical purposes, I've never noticed anything, but then, I don't have the knowledge and experience that you guys do, and that's why I'm deferring to you..............so what should I do????? Leave it, or try to exchange it for a newer one????

Thanks in advance for any info......it's GREATLY appreciated!!!!!
 
I think it's when you pay that much for a light, you'd expect it to be pretty good and be free of minor problems like the doughnut hole.

If you like the light and it isn't visible in use, then keep the light.

Have you though about a drop-in for you Z2? Or do you already have one.

:welcome:
 
I think it's when you pay that much for a light, you'd expect it to be pretty good and be free of minor problems like the doughnut hole.

If you like the light and it isn't visible in use, then keep the light.

Have you though about a drop-in for you Z2? Or do you already have one.

:welcome:

Thanks for the advice....no, I don't really notice it in use...so I guess if it's simply and only a matter of noticing on illuminating white walls, then it doesn't make a difference.

As for the "drop-in" for the Z2.....please explain....I have no idea, but since I love that light, and use it ALOT, I may very well be interested.

Thanks again, and thanks for the welcome.....I see me really liking it here!!

edited to add: Gunner12, I love your sig-line!!!!!!
 
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A drop-in would be a complete lamp (or led) assembly that takes the place of the P60 or P61 in your Z2. Many SureFires are based off the P60 (or D26) lamp assemblies. 6P, 9P, C2, C3, G2, G3, G2Z, Z2, Z3, D2, D3, M2. A few of those have been discontinued and several are offered from SureFire in an LED format.

A drop-in would be a module that literally "drops in" to your existing light. There are several drop-ins made by LumensFactory and there are a TON of aftermarket LED drop-ins.

Complete list HERE
 
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Thanks for the advice....no, I don't really notice it in use...so I guess if it's simply and only a matter of noticing on illuminating white walls, then it doesn't make a difference.
Indeed. If one finds that the beam has a distracting 'donut' in use (or if the use is white wall hunting) then contacting SureFire to see whether they can help resolve the issue is valid.

Otherwise I consider there are far better things to be fussing over.
 
I've only ever owned two U2's and still own one of the two that I had. I never found the donut hole bad enough that I couldn't still enjoy the light. I sold the light with the least donut hole but my remaining light is perfectly usable and I rarely notice or think of any beam issue while performing the occasional task with it. I found that the tint to vary more with the U2 than the beam shape.
 
matt0 explained the drop-in thing pretty well.

As the name says, it literally drops in to what ever light the drop-in is supposed to fit in.

Some are Incan, from what I seem many of them are meant to be used with rechargeables which the stock ones can't stand. Others are LED for increase in output and/or runtime. Most of the LED ones are recommended to be used with a metal body light to help remove heat from the high power LED. Without this the LED could overheat and shorten the life of the LED and cause it to be dimmer.
 
I have owned a ton of U2's (Probably 10 total) and I currently have 3 of them at my house. I was, at one time, very sensitive to the "donut holes" that were present in all of my U2's and in my L5's and L6's. I wasn't sensitive because the light didn't work well or because the the donut hole was distracting; I was sensitive because I heard reports from other CPF'rs about their U2's that did not have donut holes and this made me believe that mine was defective.

What I found was that the donut holes were normal for Lux V lights and I began to appreciate the U2 for what it is; one of the finest lights ever made.

Take care.
 
Thanks, everyone, for all your replies!!! I appreciate all the help!!!

Thanks, :)> !!!!! Your explanation makes a ton of sense. I knew that there had to something more to the fact that so many U2s had the d.h.'s. Now i just have to research just what a "Lux V" light is. :thinking:

You guys rock!!!
 
A Lux V is a Luxeon(company) V(model) LED.

It is used in many different lights like the Surefire U2 and was one of the brightest LEDs when it came out. Essentially 4 Luxeon I or III, I don't remember, one one slug.

I has a higher forward voltage(about double) then most white LEDs because of how the dies are arranged. 2 strings of 2 dies in series.

But now it is a last gen LED. The newer LEDs can match or exceed(depends on the flux bin of the Luxeon V) it in output with half or less power. The newer LEDs are twice or more efficient then the last gen LEDs.

More common current gen LEDs:
Cree XR-E P4-R2 flux bin
Seoul P4 U and U2 flux bin
Seoul P7 C flux bin
Luxeon Rebel 80 and 100 flux bin
Luxeon TFFC(flip chip) 180 and up flux bin

More common last gen LEDs:
Luxeon I
Luxeon III
Luxeon V
Luxeon K2

The Luxeon I, III, and some K2s to current gen LED swaps are best done with the Seoul P4 because they have almost the same emitting pattern.

Flux bin is how efficient/bright a LED is. LEDs are made on the same assembly line and are sourted according to color, performance, and tint. Some companies have even more catagores like Vf or forward voltage. LED bin codes.
 
I've only ever owned two U2's and still own one of the two that I had. I never found the donut hole bad enough that I couldn't still enjoy the light. I sold the light with the least donut hole but my remaining light is perfectly usable and I rarely notice or think of any beam issue while performing the occasional task with it. I found that the tint to vary more with the U2 than the beam shape.

I'm the CPF'er that bought Patriot's other U2 from him. My U2 has a very slight donut, but it is barely noticeable and is not a problem at all for me. I use it a lot without ever really paying attention to the donut. If your U2 donut is barely noticeable, that's about as good as you're going to get. I've got two other LuxV lights, the L4 and the L6, and they also have barely noticeable donuts. It is just par for the course. That is the nature of a Luxeon V light(unless you get really lucky and happen to have one with no donut... very rare). Enjoy your U2. It is an amazing light.
 
I'm the CPF'er that bought Patriot's other U2 from him. My U2 has a very slight donut, but it is barely noticeable and is not a problem at all for me. I use it a lot without ever really paying attention to the donut. If your U2 donut is barely noticeable, that's about as good as you're going to get. I've got two other LuxV lights, the L4 and the L6, and they also have barely noticeable donuts. It is just par for the course. That is the nature of a Luxeon V light(unless you get really lucky and happen to have one with no donut... very rare). Enjoy your U2. It is an amazing light.


Thank you, my friend!!
 
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