U2 Ultra: 85 or 100 Lumens ??

U2 advertisd as 80 or 100 lumens?

I got a new U2 about a week ago. I know that the "old boxes" advertised 100 lumens and now they advertise 80 lumens, but this box says "2 to 100 lumens" on it. What gives? It is a new one -- it's SN 8264. The website still says 80 lumens..... :huh2:

The website says 85, the package it came in says 100.

Which is it?

BlueLED said:

The website says 85, the package it came in says 100.

Which is it?

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It's probably close to 100 lumens as Surefire always underrates their flashlights. If it's bright and doesn't have a major doughnut then I wouldn't worry about it.

RJM

What's a donut and/or rings?

How can I tell if my LED is working as is at all power levels? I have shined it through the blue filter and it has a blue core and pretty evenly-distrubed lighter blue outside. Circle looks sharp.

White light is pretty consisten through the circle.

That good? Andy easy identifiers for a perfectly-working or broken LED or Surefire light?

I found U2 is much brighter than L2 i used to own. Unless L2 is not 100 Lumen. U2 is a real performer. So much fun with it.

Re: U2 advertisd as 80 or 100 lumens?

one of those mysteries of the universe.....:shrug:

Re: U2 advertisd as 80 or 100 lumens?

Trying to be helpful here and advise you of the situation as I understand it.(BTW I'm not a Surefire guru of which there are loads here on CPF) Anyway as I understand it the original U2's were advertised as 100 lumen. Later Surefire revised that to 80 lumen. Now it is advertised as from 2-100 lumen.

I suspect that the Surefire's website (which is notoriously slow to be updated) reflects the 80 lumen and hasn't been altered.

Of course the most likely definitive answer would come from Al Windler so you could try asking him?

Hope this helps?

Doug

BlueLED said:

What's a donut and/or rings?

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If you already own a U2, and you don't know what the donut is, don't ask. Either yours doesn't have one, or you can't see it.

If you are lucky enough not to have one, we all hate you.

If you just can't see it, don't go looking for it. Once someone points it out to you, it's impossible to stop looking at it.

Basically, the donut is just a dimmer spot right in the middle of the beam. Due to the way the Lux V is built out of four cores, there's going to be a dim spot right in the middle of them. If the reflector was designed to be tightly focused, you'll likely see that dim spot projected in the beam. It's a lot more obvious when shining the light on a bare white wall. It's a lot less obvious when using your light to look in that jumble of shoes in the bottom of a dark closet. It tends to disappear when the U2 is held about two feet away from the wall, but gets larger as the wall gets farther away. It's also commonly more noticeable on the lower settings than on the highest.

I've tried to photograph the donut in mine, but for some reason it doesn't like to show up in digital photographs. It always seems a lot worse in person.

http://home.comcast.net/~tbower/donut.jpg

BlueLED said:

The website says 85, the package it came in says 100.
Which is it?

Click to expand...

As with any LED light there's apparently some variation. However it's unclear if Surefire made a manufacturing change, e.g, a different emitter at some point.

The U2 tested by Flashlightreviews.com was not especially powerful: 55 overall output units, roughly equivalent to 80 lumens.

I've measured my U2's ceiling reflected light with a lux meter, and compared to my HDS EDC U60, which is supposedly calibrated to 60 lumens. That indicates my U2 is outputting TWICE what the U60 does, in theory 120 lumens. Conservatively, well over 100 lumens.

If anyone else has a U60/B60, a U2 and a lux meter, would be interesting to see your results.

Re: U2 advertisd as 80 or 100 lumens?

More info in this thread:

https://www.candlepowerforums.com/threads/100524

Re: U2 advertisd as 80 or 100 lumens?

Similar threads merged ...
bernie

joema said:

If anyone else has a U60/B60, a U2 and a lux meter, would be interesting to see your results.

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I've got a U2 and a B42. I've left my notes elsewhere, but IIRC, I saw about 8 lux reflected off the ceiling from my U2. The ceilings are tall, and the U2 was running an 18650 cell at the time. My B42 on maximum output gave me about 5 lux. I figured if I had used primaries in the U2, it might put out about twice as much as my B42. That should be roughly 80 lumens, or exactly what Surefire claims.

I also measured lux (throw) at roughly one meter. My B42 gave me numbers which are almost exactly the same as those seen on the flashlightreviews.com website.

Ty's HDS Basic 42 (lux @ ~1m)
-----------------------------
Max 1030
Prim 274
Sec 70
Mini 6

These numbers are from memory. I'll come back later and edit my message once I find where I wrote the down the actuals. They do show that my meter gives approximately the right numbers. My U2 gave about 1760 lux on primary cells, and 1410 with a partially spent li-ion. Based on the numbers I'd say its output is definitely a solid "average" at best, as far as the U2 goes.

The output rating is nominal at best. There is variation with incandescent as well as LED light sources. SureFire tend to have conservative ratings.
Few flashlights (no SureFires) are tuned to a specific output so a rating is a guide more than a stone-set value.

If you're happy with the tint and beam quality then that is, in my humble opinion at least, more important. If we were to shine all the U2's at once against a wall (long wall) then I doubt we could spot the difference in outputs but we could spot differences in beam tints and "donuts".

Al

Just got my U2 yesterday!
Very nice!
The donut is actually very small (and yes, tested that on a white wall), so it's a keeper!
My U2 box inidcates 2 to 100 Variable Lumen Output, 1 to 40 Variable Hours Runtime (this is on the back, top corner).

Adjusting the ring through the settings is smooth, no stops, no noise.

The Operator's Manual is Revision A 11-1-2004, and contains the same info, 2-100 Variable Lumens, 1-40 Variable hours.

Ty_Bower said:

I've got a U2 and a B42....I saw about 8 lux reflected off the ceiling from my U2. The ceilings are tall, and the U2 was running an 18650 cell at the time. My B42 on maximum output gave me about 5 lux...My B42 gave me numbers which are almost exactly the same as those seen on the flashlightreviews.com website.

Click to expand...

I posted a response last night but it's gone now. Maybe the thread merged wiped it out?

Anyway, unlike yours my U60 only does about 50-55% of the Flashlightreviews numbers, on all four brightness levels. That's measured at exactly one meter.

So I don't know if my U60 is weak, my U2 is strong, or my lux meter is off. I'm confused. However my U2 gives about the same ceiling and wall reflection lux as my Streamlight TL-3 with new batteries. So maybe my U2 is strong.

OTOH my U2 did 1330 lux at exactly one meter, so maybe my meter just reads low. Even if that's true, I'd expect the relative difference between two lights to be somewhat accurate, even if both read low.

Can you try a B42 vs U2 wall reflection test? You'll get more significant digits than a ceiling test. Use fresh batteries in both if possible.

joema ... the merging of two threads keeps all replies but arranges them in chronological order. You can find your posts above. I hope
bernie