But recently I’ve discovered, through modding the TK61, that it will take at least 15M to really get an accurate reading. 30M is going to be tough for a lot of people. I can probably swing it fairly easily in one of our barns or even outside under optimum conditions, but it will take some set-up of course. I might go ahead and set it up for easy consistent results in our barn. I’ll check it out, now that the family of foxes have moved on…
thedoc007, welcome to the forums!
Glad you found the thread interesting and joined the discussion. :beer:
[quote=GeoCan46] RaceR86 seems to be concerned with Peak Throw (kcd) numbers so the distance used should be the major factor not the lightbox calibration. [/quote]
How the lightbox/sphere, etc is calibrated is a concern when it comes to lumen. How the lux meter is calibrated is a concern when it comes to kcd numbers. This thread is about both of those numbers. Some of the guys with the highest lumen numbers also have the highest kcd numbers. In some cases I talk about both at the same time. Sorry if im not being clear.
IMO lux meters needs to be calibrated as well. Most guys seems to just go with what the meter tells.
I do lux readings at 10m. After 30 seconds. Usually between 30 seconds to 1 minute, but as close to 30 seconds as possible. I either use live view or a recording DSLR to see what happens/happened at the lux meter all the way from startup to one and a half minute while im searching for the highest readings.
I think you need to get your numbers calibrated to ANSI standards and not "real life in texas". 0:)
I use a LX1330B for throw and lumens… I agree - if anything the throw is a little bit high on both the LX1330Bs I have… FWIW I do get a reading of 938kcd on the deft x that Michael certified at 931k.
I will be the first to admit that my sphere is quite crude - its made from paper mache and spraypaint… I have fairly high confidence in it though since I used a number of ANSI lights to calibrate it and they all landed within a few % of each other in terms of a corrective factor. Aside from buying a professional integration sphere, its as good as it gets for now. I can reproduce the same numbers - usually within 1% every time. If nothing else the database I have over on vinhs forums has grown large enough that it should be able to serve as a relative comparison of many lights that hopefully can be useful to the community 
And yes - I would rate the FET driven securitying T6 4c model as 3800 ANSI OTF - but remember - I have a UCL installed on mine… stock should be a little lower with a regular glass lens
JMpaul320, im curious. Have you measured stock TK61 and stock K50?
How would you compare your lumen and kcd numbers compared to selfbuilt? Or compared to others?
I’m a bit late to the party (er, thread)… but I’m totally onboard with trying to get better calibration for everyone.
I have a cheap HS1010A lux meter and so far have only made a simple milk carton light box. Also, for really really low readings (too dim for the light box), I’ve found that it works reasonably well to simply hold a medicine bottle cap over the lux meter and press a light directly against the cap. Yes, it’s prone to errors due to beam pattern, but it’s better than any other really-sensitive approach I’ve tried.
The plan is to make a proper sphere sometime, but I’ve been busy.
As for calibration, I use the lux readings directly (tested first with some lights of relatively well-known throw, decided the values were close enough). For lumens, I’m using a simple linear correction factor chosen to most closely match my Zebralights. It’s not the greatest calibration, but so far it has been surprisingly okay for “ballpark” purposes.
I hope to do a better calibration curve like what selfbuilt did, but again have been too busy so far and don’t really have enough data points to do it properly.
On a related note, I made a publiclab spectrometer… and getting meaningful readings from it is surprisingly difficult! Tiny changes in the angle of the light or the meter can produce huge changes in both the magnitude and the shape of the spectral histogram, and it gets overexposed pretty easily. I mean, looking at a red XP-E2 it gave me a clean result totally within Cree’s spec… but comparing two different white LEDs is really difficult even if one is 65CRI and the other is 90+.
Ansi FL1 “standard”, extreme example chart.
if one take it on 30 seconds, other using 1 minute and another one on 120 seconds, what is the number for this one ?
It’s from Chloe’s review for Olight ST25 , about same pattern with Bigmac_79’s
Imo, the best measurement should be like this
I do not have a stock tk61 or stock k50 to compare to unfortunately…
most of the lights I have measured so far have been modded lights (aside from the ANSI lights used to calibrate the sphere)
I would be very interested to test some of the SAME lights that selfbuilt measures (or other members measure) with my setup and equipment - just to see how they compare. I think that would be informative. The few OSTS lights that I tested from Michael were with 4-5% of his ANSI readings he sent along with the lights. (TN31mb & deftx). Also - I was able to reproduce the Tom E lux measurement on a Modded Maxtoch he sent me within 3%.
This could all just mean we have the same light meters though LOL.
JMpaul320, just curious, again.
You have measured many ANSI rated lights in order to get your lumen calibration. Did you try to calibrate your lux meter in the same way, using the ANSI rated lights as reference?
Im not surprised your lux reading were close to Tom E. Did you compare lumen as well?
No - I did not calibrate for lux the same way - I could try I guess - I just thought I would get a wider range of lux across lights… I guess it could be my next project
Tom E Maxtoch numbers
Panasonic PF
lumens: 1,615 at start, 1,540 at 30 secs,
throw: 358 kcd, measured at 5 meters (did get 344 kcd on an earlier test)
Jmpaul320:
Samsung 20r
1538@ turn on
1425@ 30 sec
626 mid
266 low
Throw - 358,000 lux
Perhaps we all just need to take a trip where we bring our meters over to someone with a lot of lights and then all measure the whole set, and calibrate our results to each other. At least then it’d be relatively consistent. But then, I think a few BLF members have already done that, more or less, with nearly-identical spheres and a single set of lights shipped around. And the results still vary.
Was that taken with the cells at 4.19V or 4.21V? What was the ambient room temperature? How deep into the IS aperture was the light, and was it dead-on or tilted? Did you measure at 30 seconds or 28 seconds? Did you let the light cool down between measurements? Etc… Even with just one light and one meter, the results still vary… especially if two different people operate the equipment.
Each person’s results are really only comparable to the same person’s other results, assuming they spend the effort to do things the same each time. I can’t say whether my D25A XM-L2 is actually 201 lumens or 141, but I can at least say it puts out about 78% more light than a L3 L10-219A.
So, to make one’s measurements more meaningful, it is very helpful to include results from several different lights at the same time, to provide context for what the numbers actually mean. The person reading it can then scale the values accordingly, if they have any of those lights available as a reference point.
Would certainly be interesting to see what you ended up with on your lux meter if you tried to calibrate it based on your stock ANSI rated flashlights. :)
No surprise to see that Tom E`s lumen number were higher compared to yours on the exact same light (About 8% higher at 30 sec).
I was expecting at least 8% difference, but strange that people who use so many ANSI rated lights can have such a "large difference". Especially when you say that you can usually be within 1% when you measure your lights and that ALL your ANSI rated lights were within a few percent in terms of corrective factor.
Just sharing observations...
All this reminds me of the story of the dolphin(porpoise?) that was found young, weak, injured. They took it in, gave it medical care, nursed it back to good health…spent 10’s of thousands on getting it ready to return to the ocean. They made a huge deal of it, had various news agencies present to document it’s release and had it tagged so they could follow it’s progress, the whole 9 yards.
When they released it, it swam off and leaped out of the water and right in front of all the cameras and scientists, an Orca ate it.
I hope there was a petition put out to get rid of all Orcas.
Point being, all the effort to be perfect is taking place in an imperfect world.
You guys do understand that I did create my baselines from “brand” name Ansi rated lights? That is almost all I and manxbuggy1 owned at the time when I made my light box. I’m saying lights by Olight, 4sevens, Eagletac, Fenix, Jetbeam, itp, Crelant are what I used to create the baselines.
Another thing to note that no light from any manufacture I’ve ever tested TWO different of the exact same series of light tested exactly the same. Meaning between brother and and I, we have or had multiples of several certain ansi rated lights. Thrunite TN31’s, Zebralight SC600, Eagletac TX25C2, 4Sevens Mini, Jetbeam BC10, Armytek Predator, etc. are just a few we have multiples of. And EVERY single time when compared them back to back, using the same battery type and charge, the two different lights will very slightly. I’ve never seen anything huge, but 5% or so is pretty uncommon.
BUT, when test the exact same individual quality light (not my brothers version of the same light) ALWAYS yields numbers with in 1% or so. So it’s not a variance in my testing method, but it is variance of the same lights produced by even quality “ansi” rated lights.
Every light from every manufacturer is going to have slightly different output period. And that should be perfectly understandable to everyone considering Cree themselves state their emitters can vary up to 7%.
So my point is that no member on this forum can ever get a testing method down to 1% accurately matching claimed ansi ratings. If the manufacturer can’t produce such accuracy, we obviously will never be able to properly produce such results.
So all we can do is get the best baseline possible based on as many quality and ansi rated lights as possible. And that is what I have done. And when I said with in 10% accuracy, I stated that is WORSE case scenario. Most lights tested with in a couple percent. I have tested many lights that matched with in 1 lumen.
Keeping in mind the 7% variance Cree allows, and human error will occur in the manufacturer even of quality lights like Fenix, Amrytek, Zebralight - having 90% of every ansi rated light I have tested to match with in that same 10%, and again the vast majority, much closer - I just don’t see how to do any better than that.
And keep in mind that other respected members like Tom E and DBCstm have tested tons and tons of lights, plenty of them ansi rated, with the same basic setup also with similar accuracy and results.
The way I see it - at a minimum we have created an easily repeatable method of testing lights that remain very consistant between many members accross the US. And those memebrs have likely tested hundreds upon hundreds individual lights as a whole. And actually quite a few of the EXACT same lights have tested between us, again producing very consistant numbers.
So, since no member here has easy access to a true integrated sphere AND would be willing and able to test hundreds of custom and modified lights - I think our testing method does the job we need it to do pretty darn good.
Ill let RMM, Tom E, and DBCstm correct me if im wrong. But they all tested TK61 to have 1200 lumen. Three different lights, three different persons, three different of your boxes. All pretty much at 1200.
That is 20% higher compared to selfbuilt`s baseline. Considering that many have Fenix as baseline, you are 20% higher compared to many of those. Unless TK61 reads a lot higher compared to other Fenix lights. But Selfbuilts measurement did not show that, nor have I seen a sign of that, and I have compared with other Fenix lights as well. If I should take my sample of TK61 and make sure my measurement was 20% too high compared to Fenix and Selfbuilt, my calibration would be so high that my others lights would read too high compared to ALL the other people who have done similar work. And they are ALL lower as far as I my observations go. I seriously doubt no one else then you guys will be that high reading on that light.
Again, Tom and DBCstm still have the highest numbers on K50.
Selfbuilt - 1450
Tom E and DBCstm - 1650 (roughly their average)
13,7% higher.
In the case with the light Tom E modded for JMpaul320. 8% higher.
If you were close to others peoples baseline, these large differences would not happen. And many people have done all the "same" calibration work, but they are more in line with each other. These numbers are not exactly within the few percent that you would expect people with similar baseline right? These are 8-20% higher. And note, im not cherry picking examples here. Im just picking lights that Ive personally been interested in, got comparable numbers, and maybe measured myself, so these numbers are fresh to me and also done by several people. The thing is, from memory, there a LOT of examples where the guys with your lumen box always have showed sign of having the highest numbers compared to others, so I can assure you, its not just these flashlights that show very high numbers.
When that is said, I have not given much thought to the type of lights differences are seen on. Could it be that especially these modern day powerful throwers have a tendency to read extra high in your lumen box/pipe thingy?
Maybe do some testing on that? This is your box right? And you all have quite similar boxes.
How is the conversion from light meter result to lumen done?
:popcorn: :-)
I like your persistance RaceR, measuring light is a very tricky business, I found that that to my disappointment too, but it is good that apart from the unavoidable measurement errors, at least the avoidable ones are pinpointed by you.
I stand accused of having some of that myself. But, in this case, you are chasing after a single fly in the middle of a stock yard.
Let me explain a few things on my TK61, and you’ll see what I mean.
When I got my TK61 I was intending to modify it, with only days before leaving on vacation and expecting to take the light with me. I’d never seen a light like this, the battery carrier set up to be able to stack a second carrier tripped me up. Right out of the box I tried taking a tail amperage, and shorted the carrier. This also did some damage to my driver. Pretty sure I said this when I first spoke of my results, but of course my memory is wack.
The first lumens and lux readings I have on paper are with 2 IRLML2502 FET’s stacked on Q4 , I got 1176.45 at 30 seconds 172.5Kcd for Lux
Then I stacked an R025 resistor for 1200.6 at 30 seconds. 175Kcd for Lux.
Then I stacked a second R025 for 1825. 269.25Kcd.
Where did you get the quote that I said mine was making over 1200 lumens? See the fault? I do not know what it was making in lumens or lux right out of the box, I didn’t take those readings and damaged it before I could.
I have gotten a second TK61, fully stock, in hand for a lux reading of 162Kcd since then.
It’s the variables that sneak up behind ya everytime…
Please, I have already made up my mind so do not try to confuse me with the facts. 
Im sorry to confuse you with facts Richwouldnt, but it seems Im better at remember what Dale is writing then he is.
Nope, I dont see the fault. Here is the quote where you disagree with what you just said:
So, either you are wrong or either you are wrong.
I can quote Tom E as well.
Id say my memory was pretty right. You guys showed stock numbers that showed about 1200.
No matter which of your numbers are actually true. Your numbers are still measurements that's far beyond the others. And that is the point. Its not imporant if you guys average out out 17 or 20% higher in that exampe. Its still way too high. And its just one of many examples where your guys are way higher compared to everybody else.
Dale, dont get me wrong. Im not here to make you into some bad guys. Im considering to try and match my numbers to you guys. But ideally, I would want my numbers to match others as well.
Ive started this thread in order to get a discussion around the topic and some awareness around the issues. If it can get everybody closer in terms of numbers then nothing would be better. It will probably not happen, but at least I tried.
You share lumen and kcd numbers all the time, I would believe its in your best interest that your numbers are as good and comparable with others as possible. We are having these discussions because I want to increase the value of your post where you share numbers by making them more similar to other people numbers.
Im not trying to work against you here. This is just numbers. Its nothing personal. So please, lets stick to the numbers from now on.