# SureFire Lumens Ratings are Wacked



## wrathothebunny (Jun 11, 2007)

I was taking a look at SureFire's website and I noticed some apparent contradictions in lumen ratings between flashlight models. The most glaring contradictions are:

E2D Executive Defender
60 Lumens
1.25 Hours
2 X 123A

A2 Aviator
50 Lumens
1 Hour
2 X 123 A

AND

M4 Devastator
225 Lumens
1 Hour
4 X 123A

M6 Guardian
250 Lumens
1 Hour
6 X 123A


OK, both the E2D Executive Defender and the A2 Aviator run off of 2 123A lithium batteries. However, the E2D is rated with higher lumen output and longer runtime than the A2. Now, SureFire is reported to list the AVERAGE lumen output - or something like that - over the life of the cells. However, the A2 is regulated, so its output should not vary, therefore peak output should roughly equal average output in its case, as the lumen output graph would look like a square waveform. In an integrating sphere test conducted by members here, I recall the A2 measuring at 70-80 lumens. WTF? Additionally, the E2D, running on the same 2x123A setup, would be expected to match the lumen output of the A2, not exceed it. 

Now, comparing the M4 Devastator to the M6 Guardian, you have a 4X123A setup putting out 225 Lumens compared to a 6X123A setup putting out 250 Lumens, both at 1 hour. So an additional 2 123A lithiums gets you 25 Lumens? Again, WTF? The M4 is reported to draw about 1.45 Amps, and this would be at about 9.6 Volts. So 1.45X9.6=14 Watts. The M6 is reported to draw about 2.6 Amps at about 7.6 Volts. So 2.6X7.6=20 Watts. So again, moving from a 14 Watt setup to a 20 Watt setup gets you an additional 25 Lumens? WTF?

Taking the LumensFactory 12V D36 Standard model rated at 320 bulb lumens - which is spec'd at 1.3 Amps at 9.6 Volts - then multiplying the 320 bulb lumens by .65 to yield 208 torch lumens - then comparing this 208 torch lumens to the 225 "SureFire Lumens" that the M4 Devastator reports - which is measured to draw about 1.45 Amps at 9.6 Volts - it becomes clear that the M4 is spec'd closer to the maximum lumen output than the average lumen output, and the extra 17 Lumens compared to the LumensFactory lamp assembly is likely due to the slightly higher current draw of the M4.

As a side note, I guess you could conclude that the equivalently 320 bulb lumen rated LumensFactory HO-9 running on 2X17670s would come within just (approximately) 17 Lumens of matching the M4 Devastator's output.


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## turbodog (Jun 11, 2007)

But they don't all have the same bulb, or bulb life.

Bulbs get more efficient as life goes down.

It is entirely possible to get an easy 20% +/- variance in output by building the bulbs differently.


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## wrathothebunny (Jun 11, 2007)

Right. SureFire's bulbs are typically expected to last, on average, 50 hours or so. Now, unless the M4 Devastators bulb is being driven so hard as to last only 10 hours (wild guess) to achieve the initial 30+ bulb lumens/watt efficiency necessary to provide 225 "SureFire" average lumens over the life of 4 lithium cells, then I expect inconsistent lumen ratings on behalf of SureFire to be the likely culprit.


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## IndecisiveFlashaholic (Jun 11, 2007)

Ok, I own both the E2D and the A2. The A2 is running regulated at ~50 lumens for about 50 minutes. The E2D runs for a little over an hour dropping off significantly throughout the runtime. This equates to the different lumen outputs. As for the M4/M6 , I own neither so I cannot say.


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## wrathothebunny (Jun 11, 2007)

Yes, but longer runtime doesn't typically involve higher lumen output, if anything, the shorter runtime of the A2 should facilitate getting more juice to the bulb to provide more lumens, not less. *Update* The E2E when measured by an integrating sphere test conducted by Arc Flashlights weighed in at only 62 Lumens after 2 minutes runtime on fresh batteries. It would appear that the A2 is actually the more powerful of the two, with higher, regulated output over shorter runtime. However, SureFire rates it lower in lumen output, thus the title of the thread.


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## DM51 (Jun 11, 2007)

You make some interesting points. The E2 _vs._ A2 difference is probably explained by the A2’s less efficient reflector (with 3 holes in it for the LEDs). One would expect the E2’s output to be more efficient.

As to integrating sphere tests, the accuracy of these will presumably depend on the light-meter used. Someone ran comparison tests of different light-meters (I think it may have been SilverFox) and IIRC it showed a surprisingly wide variation in readings, so discrepancies could easily arise that way.

Maybe mdocod will be able to help with answers here.


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## kakster (Jun 11, 2007)

Regarding the M4 MN60 and the M6 MN20; I own both lights, and the M6 is easily more than 25 lumens brighter than the M4.

Also, because the M6 runs what is essentially a double capacity battery against the M4's single stack of 4 cells, the batteries in the M6 are put under less stress which results in the MN20 running whiter, brighter and for longer. I would expect a output/runtime graph for this bulb to slope down more gently than the equivalent graph for the MN60.

And yes, Surefire's specs do tend to be all over the place and subject to change (see past threads about the L4 and U2 60/100 lumen ratings), but you can safely expect performance to exceed the published specs by a small margin.

As useful as these specs are, they are only guidelines, and nothing beats trying the actual light for yourself.


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## wrathothebunny (Jun 11, 2007)

Thanks for your input comparing these two torches and confirming the variability in SureFire's lumens ratings! I would agree that as a general rule, SureFire specs will at least match if not exceed real life performance. The M6 I imagine is a prime candidate for that, as I suspect that its standard output greatly exceeds 250 lumens. However, in the case of the M4, I would consider it - by SureFire standards at least - the most overspec'd flashlight in their lineup. I would predict that it can sustain 225 torch lumens for only perhaps the first 10 or so minutes of its runtime, then dropping substantially thereafter. This would be the one case in SureFire specs where "surefire lumens" barely equals initial "torch lumens."


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## carrot (Jun 11, 2007)

Surefire lamps are spec'd to last 30 hours.


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## wrathothebunny (Jun 11, 2007)

They may be spec'd to last 30 hours, but reports here at CPF suggest average 50 hours typical bulb life. This would be consistent with SureFire's habit of underspec'ing their lights.


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## kakster (Jun 11, 2007)

Actully, a while ago, a bulb designer stated on CPF that the MN60 was the most efficient lamp made by Surefire.


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## Owen (Jun 11, 2007)

wrathothebunny said:


> They may be spec'd to last 30 hours, but reports here at CPF suggest average 50 hours typical bulb life. This would be consistent with SureFire's habit of underspec'ing their lights.


This would be consistent with people just making stuff up as they go along to make it sound like they know something they don't-a fairly common source of "facts" around here. 
Most users wouldn't have the slightest idea, and I doubt many of us here actually keep track of how many hours runtime our lamps have on them, and we're the nerds:ironic: I sure don't--it'd be next to impossible considering the way I swap out lithium ion rechargeables.


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## wrathothebunny (Jun 11, 2007)

What gives with the hostility? Listen pal, the 50 hours bit wasn't supposed to represent a hard-core statistic vetted over multiple runtime tests across various surefire models, ok. It was meant to reflect that SureFire bulbs tend to last a long a#@ time and often exceed their spec'd 30 hours. There are several individuals in these forums who report using their SureFire for years going through well in excess of thirty sets of batteries on their torch without needing to replace the lamp. Now, could their memories be fuzzy, as I'm sure they haven't actually logged all battery use in a book? Of course. When I provide accurate information pulled from current draw tests, integrating sphere tests, published specifications, and the like - and then you pick at the one stat that I vaguely gather from scattered reports in these forums - well, it doesn't reflect too well on your good self, sir.


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## leukos (Jun 11, 2007)

kakster said:


> Actully, a while ago, a bulb designer stated on CPF that the MN60 was the most efficient lamp made by Surefire.


 
I could believe that statement. Lumens Factory has said similar things about its own line up. Higher voltage lamps are often more efficient. I am also one of those nerds that counts hours on some of my lamps. I find SF lamps typically last over 60 hours in my setups. Silverfox had similar results when doing tests for his NiMH version of the B90.


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## wrathothebunny (Jun 11, 2007)

Thanks for backing me up on the SureFire bulb longevity thing  Concerning the M4, yes, higher voltages can lead to more efficient bulbs, but not enough, of course, to bridge the gap between a 14 watt bulb and a 20 watt bulb to reach just shy of 25 lumens the output of the 20 watt bulb.


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## sig-in-tx (Jun 11, 2007)

You also have to take suffice area of the reflector also.


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## wrathothebunny (Jun 11, 2007)

Yes, both the M4 and the M6 have a 2.5 inch diameter turbohead reflector.


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## JanCPF (Jun 11, 2007)

I'm not questioning yours and others observations, but bare in mind that loss in wires, battery terminals, bulb terminal and switch is greater when you use low voltage and high current, than when you have higher voltage and lower current (Ohm's law). The electrical path in the M4 may very well be more efficient than in the M6 due to this fact. :shrug:

Jan


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## mdocod (Jun 11, 2007)

there are a LOT is issues at play here with SureFire lumen ratings..

and you're right, it's almost whack and very confusing....

for starters..keep in mind that SureFire Lumen ratings, and their "de-rating" is not done the same for every lamp, they probably know how bright they are, but purposely down rate to nice round numbers that sound good for marketing purposes, I can almost guarantee you that they have no formula or specific method whatsoever of coming up with those numbers other than making sure it's honest by saying a lower number than it is in reality, and using nice "round" numbers that sound fancy.




> Now, comparing the M4 Devastator to the M6 Guardian, you have a 4X123A setup putting out 225 Lumens compared to a 6X123A setup putting out 250 Lumens, both at 1 hour. So an additional 2 123A lithiums gets you 25 Lumens? Again, WTF? The M4 is reported to draw about 1.45 Amps, and this would be at about 9.6 Volts. So 1.45X9.6=14 Watts. The M6 is reported to draw about 2.6 Amps at about 7.6 Volts. So 2.6X7.6=20 Watts. So again, moving from a 14 Watt setup to a 20 Watt setup gets you an additional 25 Lumens? WTF?



Keep in mind, again of course, that part of this phenomenon is purely based on the way SF is marketing the various setups. But on a side note, it is very common for 12V lamps to be more efficient than 9V lamps, so on a lumen/watt comparison, the MN60 is probably a more efficient lamp than a MN20. Another important point to make, is that the MN60 draws more power than their other "1 hour" rated lamps, like the MN15 and MN10 and P90, which are all more like 1.2A, not ~1.45A... so technically speaking, The "1 hour" rating is just a ballpark figure that sounds nice, it's probably closer to 45-50 minutes... compared to the 6 cells driving the MN20, which probably does last the full hour in most cases. 



> Taking the LumensFactory 12V D36 Standard model rated at 320 bulb lumens - which is spec'd at 1.3 Amps at 9.6 Volts - then multiplying the 320 bulb lumens by .65 to yield 208 torch lumens - then comparing this 208 torch lumens to the 225 "SureFire Lumens" that the M4 Devastator reports - which is measured to draw about 1.45 Amps at 9.6 Volts - it becomes clear that the M4 is spec'd closer to the maximum lumen output than the average lumen output, and the extra 17 Lumens compared to the LumensFactory lamp assembly is likely due to the slightly higher current draw of the M4.





you are trying to compare LumensFactory numbers to Surefire numbers... which is difficult.. LumensFactory numbers are based on a specific voltage at the lamp... 320 lumens of that 12V D36 is dependent on several factors.. mainly, cell performance and resistance to the lamp. A difference of 3% voltage at the bulb will make the difference between a lamp having a 20 hour or 30 hour lifespan, and will have about a 10% impact on brightness. So merely changing the brand of cells you are using can change these numbers dramatically, as their are some pretty big variations from 1 cell brand to the next.... 





I should point out that I have made the same observation that it *appears* that the MN60 and MN61 lamps are the *least* de-rated of the SureFire lamps... but again... I think this is purely a marketing thing. We all know that the SureFire MN16 and MN11 are also rated 225 lumens but for only 20 minutes on 3 cells, how come adding 1 cell would bump that up to an hour of runtime at the same output?! well.. part of it is that like I said before 12V lamps are more efficient, and part of it is that as you reduce the load on a CR123, you gain overall power availability. BUT... the reality is that the MN11 and MN16 are more like 375-425 bulb lumens, while the MN60 is going to be more like 350-400 bulb lumens... (ballpark figures)... but from a marketing standpoint, making the M4 LOLA look as bright on paper as a M3/T HOLA is just good marketing, so they choose a number that both lamps outperform by some amount.


On the subject of the M6, the MN20 is about a 7.4V lamp ~2.5A on CR123s. It's about 19W and closer to 425-475 bulb lumens / 300 torch lumens, while the MN21 is about a 6.75V ~4.9A lamp, about 33W, somewhere around 800-1000 bulb lumens (500-650 torch lumens) depending on the cells you use.


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## wrathothebunny (Jun 11, 2007)

Thanks for weighing in Mdocod! I think you make excellent points. To follow up on the M4/M6 lumen discrepancy, users such as Kakster report a noticeable difference in light intensity output from the M6 compared to M4. Previous discussion has touched on the issue that our eyes aren't as great at discriminating between different levels of light - taking at least a 50% increase in light for us to notice a difference - though perhaps ymmv. Therefore, I would submit that the M6 is a good deal brighter than the standard M4.

In comparing to the lumen factory 12V D36, what I was merely attempting to establish is that such a setup is designed to be run on 4 CR123A batteries, not rechargeables, as is the M4. The LF 13V lamps are designed for 3x3.7V configurations. So in terms of battery input power, they are comparable. In terms of efficiency, the LF lamps should be at least as efficient as their SF counterparts, so a 12V D36 LF ought to be ballpark comparable to a SF 12V M4 - in terms of efficiency. From there, you can adjust the lumens a bit upward for the M4 based on its higher current draw, and get to what ought to be the equivalent LF bulb lumen rating. So the MN60 would weigh in at somewhere between 350-360 bulb lumens, which falls at the lower range of your estimate in your post. In any case, I think you can see that unless SF is using technology that exceeds even LF efficiency, that the M4 is spec'd at max torch lumens, not derated torch lumens. So the derating formula that SF applies to most of their lights is not just toned down, it is not applied all together to the M4 IMHO.


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## mdocod (Jun 11, 2007)

I'd agree that it's very possible that the MN60 is the one lamp in the lineup that may not really have any typical SF de-rating at all. good observations wrathofthebunny!


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