Lumen and lux measurements, why cant we all try to be on the same page?

I recently purchased an HS1010A. I haven’t started any output tests but have completed throw numbers for all my lights.

I practiced for a while until I found I could get repeated, consistent results.

I had a few lights (Jacob A60 and two T08s) that I measured before and after mods. The mods I did on all three lights were pretty much standard affair, higher amp drivers, de-domed emitters, copper, resistance mods, etc.

I was surprised when I started comparing my numbers to similarly modded lights by others. With all 3 lights I found my stock numbers were a bit higher and modded numbers were significantly lower.

I did not expect in any way to be matching the kind of throw attained by some of the folks here but thought I would at least be in the ballpark.

I’ve decided as long as I can produce consistent results I can use my numbers to quantify my mods. That’s really all I wanted to do with the meter in the first place.

It might be agreed that Texas Pyro has some of the best testing equipment amongst us. Perhaps he will agree to test a light, any light, and see how it compares to the testing we do at home? I don’t have fancy computer print-outs, and yes, sometimes I can barely read my own notes even if I can reliably find them.

But wouldn’t it be interesting to pick out, say, the SupFire M6, charge up the cells and run my tests then charge the cells back up and send it to TP for his run and see how the 2 compare? TP would then argue that his expensive equipment was right, however the numbers fell. :wink:

For me, the lightbox tells me what the light is doing when I get it, and then how much difference my mods made. If the difference is not what I expected, I then check ground and other issues and test again, sometimes then finding the expected results, sometimes not. But it’s a guideline, for me, right here, doing the work and then confirming or busting whether the work was worthwhile.

Yes, I use a LX1330B. You will probably find that myself, rdrfronty, Tom E and Richard all have similar results from lights, because we’re all using the same meter and same base system. rdrfronty and manxbuggy1 spent many hours, days, weeks even, testing as many verified lights as they could get their hands on. (and their hands hold a LOT of lights!) My own box was verified against theirs, and with 20 or more of their own verified lights. So I feel confident that the results are accurate enough for me to base my builds on.

I don’t think any of us has ever said “THESE ARE ABSOLUTE NUMBERS!” Because we know the variables are everywhere. I can almost guarantee that you get a major factory to test a light, chart the numbers then send it to me, and after I test it and write everything down, send it right back to em for a second round and their own numbers will not match the first run. It’s just the way these typically work. The LED get’s burned in, the cells get some age on em, the driver has it’s own quirks and oddities as it’s components get hot and cool down. And such is the way of life.

Maybe I can build one of the Eagle Eye X6 lights and test it, then send it around to everyone else that has a box and we can average all the numbers, compare notes, and adjust our multipliers accordingly so we can all be on the same mystical page….

A VERY interesting thread as I have just had RMM modify a group of lights for me and I asked to receive his sphere results for all of the lights he did for ALL levels, not just maximum. Some of the max readings were higher than I expected and some lower but at least I now have a record of what the lights were calculated to be putting out based on Richard’s equipment and measuring technique.

From our email exchanges I got the impression that Richard uses his sphere the same way that Dale says in his post, as a reference for checking that his light modifications are putting out what he expects based on experience. Is it dead on to ANSI, almost certainly not. Is it in the same ballpark? I hope so. Just based on Cree binning specification limits I would expect ANSI spec lights to give different results for different individual lights even in a certified lab with NIST calibrated equipment.

A max modded SRK soup can triple and a max modded M6 were very close which I would expect with the same LEDs and batteries in both and basically direct drive on maximum output. Both within 1% and about 4600 Lumens. I have seen similar readings for a heavily modded M6 from another source. The champion he did for me though is a Supfire L1 which gave a reading of 7000+ lumens max and it now has the latest 7 levels RMM offered firmware in it with “hold for off” from all output levels. Even if optimistic that is one hot light and with a MUCH better UI IMO than the original.

Added:

All the tests RMM did on my lights were done with Sony VTC4 unprotected batteries which are high current low internal resistance batteries. Per my understanding the use of these or similar high current low resistance batteries can substantially increase the output of direct drive in highest mode lights such as most soup can lights are.

I had some conversarions by email with a very friendly guy from a light testing company about how flashaholics measure their output. He was quite impressed by the level of knowledge there is around here, and the testing equipment we make, but 1) he warned about the bad colour filters of cheap luxmeters, giving inaccuracy for different wavelengths, and 2) he could not find out how on earth we dare to use the word 'lumen' without going to a test facility to calibrate the equipment (this was not because he would make money from that), I guess he was not at all impressed by the accuracy of ANSI-numbers going with flashlights.

It will be impossible to get numbers accurate enough to compare one person's readings directly with another person's, not with home-brew equipment. Accepting that the numbers don't mean anything other than when compared to numbers that came from the same test setup, and are relative, is a much better/safer situation.

I have a CT-1330B, I only use it for ceiling bounce lux, and only use it to compare two or more lights in the same session - I try whenever possible to not compare a current reading to one that was taken days or weeks before. Better to assume they won't be comparable than to assume they might be when they really aren't.

Actually I still have the ambition to get my integrating sphere numbers real, within 1% of reality. I admit that still can't guarantee anything close, but maybe one day......

(not soon though :-( )

wiki ses: Lumen = Lux·m²

so why not meassure how “enlightened” one m² is when poining our guns at it? :wink:

what about using a white cardboard circle with 1 m² (1,128m Diameter) or 0,75m² (D=0.977m)

mount that “under the sky” so no reflections from somewhere else (dark ground or gras will do)

have a given distance (1 or 0,5 m ) between the Front of the light and the “ceiling”

results are now more comparable…

(excuse my drawing - right now i am carring my sleeping baby and did this walking around…)

for sure we have to find out the exact distances, but this looks cheap, easy to build and should give a BLF-Constant
-> how much light is my light

Is the exact same type of white cardboard/posterboard/paint available everywhere in the world, all with the same reflectivity? If painted, even with the same brand and type of paint, the number of coats and thickness of each coat and the total paint thickness and the surface finish (brush or roller? WHICH brush, coarse bristle or fine? which roller??) will all change the readings. Still too many variables. Assuming they will be the same when they really aren't will only make things worse.

“What gets us into trouble is not what we don't know, it's what we know for sure that just ain't so.”
—Mark Twain

And does that white paint / cardboard reflect all visible wavelengths equally well?

I really like that Mark Twain quote, it applies painfully well to these problems

Ill just start with saying that my observations that lead me to starting this thread is done over the course of about 1 and a half year. Its way more than "some guy had a light with that many lumens with those emitters, and some other guy had a fairly similar light with that many lumens and and some other emitters" and then drawing conclusions.

Im not claiming to be correct. My observations could be a off, and my thoughts based on those observations could be even more off. But I think that many of the variables will average out, and some clear patterns can be seen. For those who thinks its imposibble to see these difference due to too many variables. I could certainly be up to taking some bets on how various peoples numbers compares to each others.


HKJ, sorry, should not have put you one the list.


Texaspyro. I pretty much agree. ANSI FL1 numbers does not mean much. They are all over the place from manufacturer to manufacturer. Some manufacturers even seem all over the place from light to light compared to others. But, if someone buys 10 different Fenix lights, and use those for calibration. And some other guy does the same. Im quite confident they will be close and "on the same page". Which makes them fairly comparable and certainly much more useful then the wide spread many have today with their calibrations. Many have used Fenix lights as a reference. And that is an example of something that can help people to get their calibration closer.

And yes, there can 30% difference in the same cheap and similar named lux meter. Some meters does have fairly good consistency though. This is why its important for everyone to calibrate their lux meters as well. But right now, I get the impression that the lux meters with the highest possible numbers have become the benchmark for many people.


I just took your number from OP in the K50 mod thread. Ryan put it there for comparisons with others. This will always happens. Someone posts a number. Others puts those numbers on a list in order to try and get useful comparisons. Comparisons will not be useful when people on a list knows that their calibration is consistently higher or lower with others. On certain lists, many readers will not be aware of who did the different numbers, and how the calibration compares.

You can always find ANSI rated flashlights that you match well with or that makes your numbers seem "conservative. But what matters is peoples averages.

Ill quote a recent post from you.

"There seems to be two camps on lumens and kcd measurments - mine, rdrfronty, and DBCStm seem to agree pretty closely, a couple of other BLF'ers also. But then there are selfbuilt's and some others that range lower."

Clearly you have noticed this as well. That is because of averages. Some people consistently have a well match. And then many other people have consistently lower numbers then you guys. When it comes to lumens especially. Who else than you, DBCstm, Richard/RMM, rdrfronty and manxbuggy have as high lumen numbers as you guys? Does anyone have a calibration that consistently puts out higher numbers?? (Personally, I have not noticed that)

Ill ask the same about lux. Does anyone, or several members have a light meter or lux reading that seems to have higher numbers then you guys, most with LX1330B? (Personally, I doubt many people with different meters are much likely to get higher numbers)

Does many people have lower nubers? (YES!)

Im not trying to prove anyone wrong. Im just saying that people are not on the same page in terms of calibration, and that changes can be made in order to get people closer.


[quote=DBCstm] Yes, I use a LX1330B. You will probably find that myself, rdrfronty, Tom E and Richard all have similar results from lights, because we're all using the same meter and same base system. rdrfronty and manxbuggy1 spent many hours, days, weeks even, testing as many verified lights as they could get their hands on. (and their hands hold a LOT of lights!) My own box was verified against theirs, and with 20 or more of their own verified lights. So I feel confident that the results are accurate enough for me to base my builds on. [/quote]

Yes, I have noticed that you guys have similar results. You guys are on the same page. Ofcourse, there will be some natural minor differences from time. On average, you guys always have the highest numbers. All of you, at least you, Tom E, and Richard have measured a stock TK61 to be about 1200 lumen just to use one example (if I remember correctly). All of you will also measure higher lux compared to stock values. While many others will be close to the stock numbers from Fenix.

The point is, if you compare your numbers with several other guys who have also spent a lot of time measuring lights and getting their calibration right. Your numbers will generally be higher on average. I expect that you guys will be roughly 10-22% higher on average when it comes to Lumen compared to say, Selfbuilt and JMpaul320. Although, there will be exceptions that will show quite similar numbers.

I cant say for sure, but selfbuilt measured Supbeam X60 to about 5100. _the_ measured it marginally higher. I would not be surprised if you measured it to 6000 lumen. I expect your measurement to show at least 5500 lumen. Selfbuilt and _the_ both measured that light to 160kcd. Spot on! I can almost guarantee that you will measure it higher.

Here your can see some of Selfbuilt work when it comes to calibration. Link 1. Link 2. JMpaul320 have a thread here. He measures lights for people, and also do a lot of measurements on vinh lights. (same light meter as you btw, with same high numbers when it comes to kcd. Certainly a difference in lumens though).

These are two examples of guys who have done calibration work. Someone correct me if im wrong, because Ill throw out some names that Im not 100% how their measurements compares as I have not studied them properly and cross checked and done lots of on paper comparison. But Relic38, JohnnyMac, _the_ in general seems to be closer to Selfbuilt and JMpaul320 in terms of lumens. Here are 5 different people who seems to be able to get not perfectly within the each other, but not that far off on average when it comes to lumen and lux. Im quite confident that these guys are closer to eachother than the "high numbers" camp.

The funny thing is that the gap between these two "camps" are so large that I on several occasions in a row have been able to put my numbers in between them. To me, that means people in the "two camps" are not on the same page.


Where should mine and other peoples calibration be pointed towards?

The issue for me, is that I don't know where I should try to aim my calibration towards out of these two camps. Morally it makes more sense to aim towards the lumen numbers that all the different people who reviews lights and independently have come up with their own calibration that seems to be somewhat similar. I believe these numbers are realistic and certainly doable based on Cree`s own numbers. I believe I would be more in line with more people who have done independent calibration work and come to somewhat similar results. I believe my numbers on average would be more comparable with ANSI numbers from different manufacturers that way too. Which means that my modded lights can more easily be compared with manufacturer ratings (even though that will often be a bit off depending on manufacturer).

But, its more temping to aim towards the guys with the high numbers. Simply because it sucks having low numbers when the typical people I compare mods with have a higher calibration. I mod lights, and most of the numbers seen from modded lights on BLF are from the guys in the high numbers camp. And that camp is growing. Tom E always used to say, that at least my numbers are comparable with rdrfronty if questioned. And for a long time DBCstm have joined. And he shares a ton of numbers. And RMM/Richard is on that same calibration. And more people want lights and numbers from him. And those people might start using those lights for reference... It seems to be a growing camp there. And that does not help anyone...

For me personally, id like to see everyone try and meet in the "Average ANSI/Typical reviewer/conservative" call it whatever you will camp. I don't see that these people will increase their numbers based on all the calibration work many of them seem to agree on, and how close they on average are to many of the lights they review.

Im not sure what the high lumen camp have to loose in order to meet the others. Except getting results that will be more comparable with a larger number of people. Which I think would benefit everyone.

I do know that if I want my numbers to be in line with most modders who share numbers on BLF, I will have to add even more to mine despite that Im already on level or slightly above many others. The lumen gap is quite large IMO.

When it comes to lux. I know that my lowest reading meter might need around 30% increase to match the high numbers camp. My other meter might need around 15% increase. (Sure, some other guys have cheap lux meters that does match lx1330B, or are not far off.) But in general, if I increase my numbers more, ill create an even larger distance to some of the people and manufacturers that Im already above.


If someone wanted to get a reference light for calibration (lumen and lux). It would have to be several reference lights, with different beams and tints, and superlow and superhigh lumen readings in order to make it worth it.

If these lights were verified and shipped around as a calibration reference to different members. Would all the guys in the different "camps" adjust their numbers accordingly so that everyone could be as close as possible??? Unless that happens its not much use.

Can it be as simple as the cells used? Fenix undoubtedly uses their own brand of cells when testing their lights. We (most of us) use the absolute best cell available with higher capacities and lower internal resistance. This can very easily make for the differences you’re seeing.

I’ve shown test results from 7 different cells in the same light, showing that the new FET drivers in direct drive or near it can be “tamed” with a lesser cell. Would this, then, hold true for the factory measurements as compared to our home measurements?

Just a thought. Maybe it’s the Texas air that magnifies the results down here, so good and pure. :slight_smile:

High discharge cells does not matter when it comes to peak output in the majority of properly regulated stock lights. Not that all premium lights are properly regulated. But many of the expensive lights with several cells often are. And many of those who are not regulated are not pushed as hard that you need high discharge cells in order to see their peak output. There will always be exceptions though.

Direct drive lights, and lights that rely on a certain voltage (that batteries will fall below) to maintain a certain amount of amps certainly makes comparisons much harder to do when people use different cells with different voltages. And that will happen. Its nice that you and many others state the cell, cell voltage and amp draw when sharing number for the direct drive hotrods. That really put things in context when measured that type of light.

There is more discrepancy in amateur kcd readings because ANSI guidelines are not followed. The ANSI FL1 standard requires measures be taken at 2m, 10m, or 30m from surface of the lens, as appropriate for the size of the flashlight head and output width. Selfbuilt and Tom E mention measuring lux/candela at 5m. Any light claiming to be a thrower should be measured at 30m, perhaps 10m for a smallish thrower. The 5m distance is a necessary amateur compromise due to the difficulty of setting up a suitable dark space with 10m or 30m distance. Most amateur kcd readings don’t even mention the distance used and are therefore all over the map.

I doubt that the premium light manufacturers that mention the ANSI FL-1 standard in their packaging and advertising are all over the map. They would have lawyers from ANSI and other industry groups coming down on their heads. Very bad for business if they want to contend in the premium light sector.

Which specific premium light manufacturers do you think are making false ANSI FL-1 claims? Can you please name 3 or 4.

I’ve been looking into this ANSI-lumen thing for a bit and find Selfbuilt’s lumen scale to be very liberal and close to Zebralight’s scale (eg, SC52). Makes good sense to use a lowest common denominator scale, in his capacity, since many manufacturers probably would not be sending him samples to test if he consistently reported their specs as overstated.

Selfbuilt doesn’t claim ANSI lumen accuracy, only comparable/relative accuracy with which I agree. Sure, he uses a lot of data points, but they seem way outdated IMHO - if you look at his data sources they include Novatac (really old), Foursevens and Fenix, but I believe BEFORE these companies voluntarily adopted the ANSI FL1 standards (eg, SB finds the recent 180 lumen Preon Penlight to be 260 lms). Also one of his data points is a reviewer, “ti-force,” which happens to be the ONLY REVIEWER I have seen that actually claims ANSI accuracy. Here’s Selfbuilt’s and ti-force’s accuracy statements:

So, for a light that they’ve both reviewed - the QP2A-X, the ratings look like:
Max: SB - 420, TF - 350
Stepdown: SB - 300, TF - 240

That’s a pretty significant difference IMHO. I personally use TF’s scale since it matches most of light collection and I can use a QP2A-X, D25A, MDC AA, or T10 (an early gen twisty) to calibrate my lightbox (any mode really). ZLs, are the most exaggerating in my AA collection, and I think Fenix is right up there too (both the SC52 and LD12 claim ~ 300 lumen-hrs [lms x hrs] efficiency across most of their modes on a AA). Here’s an example test between the ZL and ET, which I found same result in my side-by-side test:

The green and beige lines are an SC52 108 lm/3 hr mode vs the D25A XML 75 lms/2.5 hr mode, and this test was calibrated using a Fenix lumen scale. ZL claims nearly 75% more efficiency (again, in lm-hrs) for virtually identical performance. As you can see, the LD12 also seems to fall well short of its claims, even if adjusted for a 2500mah NiMh, and would come in at ~158 lm-hrs on an TF/ET/2000 mah scale, almost half the 308 lm-hr marketing spec.

JIMHO, of course - my collection is most composed of smaller 1xAA/14500 EDC lights, so I can’t comment on the more powerful lights in the higher lumen ranges. YMMV and all. :slight_smile: But yeah, the huge differences in marketing “ANSI FL1” is maddening.

What about a cheap reflector type telescope that funnels all the light into a photo sensor? That would concentrate the light going down the tube (I would think) without the issue of hotspots.

Something like this…

Then calibrate the readings from there. I dunno just thinking :slight_smile: Maybe filter out the uv

The solution to do fair measurements of light flux regardless of beamshape exists: it is the integrating sphere :-)

Guys, I just want to say a few things here. I know my light box and other members light boxes are not perfect. No doubt. But, I do know the setup I use will get you pretty darn close numbers. I have tested I’d estimate close to 75 Ansi rated lights in my box. At least 90% of those ansi rated lights have tested with in 90% of their “official” lumen ratings. I’d also estimate that 1/2 of the Ansi rated lights I have tested, post numbers falling in the 0-3% range of matching the manufacture’s rating.
As far as I’m concerned that’s PLENTY accurate enough for me.
And as mentioned above, many members have similar setups to mine - Tom E, DBCstm, etc… And knowing these guys and their dedication to testing and modding - I have no qualms taking any readings they post as being VERY close to ansi specs.
Another point I must add is about the meter. The very popular (and falsely accused) LX1330B meter is NOT the only meter I have and use. I also have an much more expensive Extech EA31. Same meter Selfbuilt uses by the way. And I have never seen my LX1330B test more than 1% off from my Extech EA31. And I’ve compared them many times with many different lights. The LX1330B might be a fairly cheap priced meter, but it’s NOT a bad quality meter. At least the one I purchased. There are a few variations out there, so I cant vouch for them all.
All this aside, the main purpose of these light boxes I and others use were try obtain fairly accurate numbers for lights that never had ansi ratings or for ansi rated lights that have been modified. The way I look at it - if my light box and meter is at WORSE CASE scenario + or - 90% accurate on the ansi rated light I ever tested, again appx 75, thats plenty good enough for me to use this setup on modded or non ansi rated lights to find a fairly accurate output rating.
After all, this isn’t brain surgery - it’s just a hobby guys :slight_smile:

Reppans used reviews by Selfbuilt and ti-force as examples of differences between measurements. Further checking of the comparable reviews, shows that Selfbuilt used Eneloops for his measurements while ti-force used Duracells. According to other BLF info about the differences between NIMHs and Alkalines, that could entirely explain the differences in their readings. This misunderstanding demonstrates the complexity of comparing measurements without identifying all variables. The ANSI FL-1 standard clearly indicates that the identification of the exact battery used is part of the measurement.

The problem is not with the measurements made by serious amateurs but with other amateurs trying to interpret those results without fully understanding the ANSI FL-1 standards and taking into consideration the measurement variables that those serious amateurs do identify.

For peak throw (kcd) the ANSI FL-1 standard requires measures be taken at 2m, 10m, or 30m from surface of the lens, as appropriate for the size of the flashlight head and output width. Some serious amateurs reasonably compromise on a distance of 5m, while others use 1m. Big throwers should be measured at the 30m distance, difficult to do outside a professional laboratory.

Even serious amateurs do not have the financial resources to follow strict ANSI FL-1 guidelines. There is a lot of consistency in the measurements of serious amateurs. They appear to be all over the map because they are usually interpreted by less serious amateurs. Interpretation of measurements must take full account of the variables and compromises identified by those serious amateurs. Serious amateurs try to follow ANSI standards, to fully identify the conditions of their tests and to acknowledge variables and compromises in calibration and setup. Our misinterpretation of the ANSI FL-1 standards and of other peoples measurements are the biggest factors in the apparent inconsistency.

The discussion should not be about adding fudge factors to make amateur measurements more consistent. We need to fully appreciate the variables and compromises that go into a serious amateur test set-up. Then we need to fully understand the ANSI FL-1 standards so that we can meaningfully interpret any measurements that serious amateurs share with us. There is no simple formula other than to rigorously follow the standards, which requires 5 to 6 figure expenditures for professional equipment and laboratories.

IMHO the manufacturers of high-end lights, who do publish ANSI FL-1 Standard measurements on their packaging and advertising, can be trusted to have followed the guidelines. The lawyers from ANSI and other industry groups would be all over them if they were making exaggerated claims while using the ANSI FL-1 designation.

If this was my job I would go for the most time-effective and cost-effective measure that solves the problem, 10% off for a light reading will hardly be noticed and is perfectly fine.

But this is not my job, it's a hobby :-D , so I'm allowed to get it to brainsurgery level for no sound reason at all, other than: why settle for 10% if with some fiddling and lots of extra time spent you can get 1% accuracy

I personally doubt 1% accuracy is possible as there are too many variables from integrating spheres with variable reflectivity depending on LED output frequency to light to light variations in a production run to ambient temperature conditions affecting LED test temperature etc. Are you using the same batteries as the factory did? Supposedly specifying batteries used for the test is part of the ANSI standard but I do not recall any manufacturer who includes that information in their advertising data. Some “White” coatings are far from the same reflectivity in the IR or UV frequencies per what I have read. As I said at the start, too many variables unless someone wants to spend the money for a certified laboratory setup and then the annual fees to keep it certified as calibrated,