Crazy question, did you try a new battery in the light meter?
Hm… I’ll give that a shot and see what happens.
Holy crap. FMcamaro that was GENIUS. Why did I not think of that. I'm hitting myself now that I almost bought a new light meter.
Anyway thanks to FMcamaro I can now retest both these lights.
The reading was the same at 5 meters and 10 meters ± 30 lux.
At 30 seconds:
TomE's Super TN31: 370,000cd
BTU Shocker w/ AR coated lens: 133,000cd
I am VERY pleased to see this number. I would agree that TomE's light meter reads a tad low, and mine a tad high. To estimate, I would say it's closer to 365kcd. This far surpasses the 250kcd needed to become a kilometer light. This sits nicely at 1,208 meters, 1321 yards or 3963 feet. Now to get a mile light (1.6km) I need to reach 647kcd. Hm, Maybe when the XPG3 comes out.
Relative to the BTU Shocker though, which I estimated conservatively at 2700 lumens, the ceiling bounce gives me 1441 lumens from the TN31. This is seriously bad ass, and in the 4°C (39°F) I can really feel the neck warming up really fast which is good! This will DEFINITELY help with fishing. I feel so excited. This is such a great light. TomE and XM-L2s really are amazing :)
Woot, great job you two!
Batteries are the culprit of wonky measurements, from DMM’s to lux meters.
Can’t believe we have been scratching our heads because of that! 
So the Nexus is reading a little low?
Is TomE’s TN31 a OSTS modded one or did he mod it himself from stock? Either way I’m keen to get one!
Yeah, looks like it reads way lower than it should, not sure if it’s my Nexus itself, or they all read low - still good to get a ballpark range though, just up it by about 19-20%. But my light meter I suspect also reads a little high, just a little.
He modded it himself from a stock XML2 TN31, it has a resistor mod (5.6A) and dedomed the stock emitter. OSTS uses an XPG2 and has I think closer to 650 lumens, and 400-440kcd.
Thanks for that info. I wonder if this is consistent through out all the Nexus 4’s. 
TomE’s is much more practical I believe.
Is the stock PCB better than SinkPads?
Apparently so - it’s thicker than the SinkPad which is why he chose to use it over the SinkPad.
Nice, thanks for your reply.
Ahh ok, so the OSTS has a pencil thin beam, where TomE’s is a thicker beam that doesn’t throw as far as the OSTS TN31? Is that right?
That would be correct, but keep in mine that the XML2 version (TomE’s version) has 2x the lumens and still illuminates things 1.217 kilometers away (to 0.25 lux, 600 meters to 1 lux). Think about how far 1.2 kilometers is. For what it’s worth, 440kcd (the absolute highest that it will be, 400k being the lowest) throws a beam 1.327 kilometers away (to 0.25 lux).
The XML2 would have a much larger hotspot thus making it more useful for spotting things. Personally I’m using it for fishing so I went for the XML2 route, as following fish with a pencil beam isn’t exactly easy (I tried with a Jacob A60).
Maybe if I was using it for signalling or shooting balls of fire then I’d consider getting the OSTS.
Glad it worked!!
Its always the easiest fixes that get overlooked!
I’ve really gotta get the lux meter out on my vinh TN31. I’m expecting similar if not slightly higher since mine runs at 6.5A.
So you take it at 5m and then multiply by (5^2) ? Was your first post calculation correct?
The meter would be on the 20,000 setting?
Yep, my formula was right it’s: distance(meters)^2*lux = lux @ 1 meter.
whoa da - just saw this thread. Actually, my throw measurements are at 4.3 meters, so I tend to get lower #'s. I was thinking your light (and mine) were like 360 kcd, judging from rdrfronty and manxbuggy1's measurements of the same lights we measured (they measures at longer distances too).
Also, that stock copper star in the TN31 is the best I've seen yet - like 25 mm, thicker than a SinkPAD, direct thermal path, screwed down, and of course I used AS5 and sanded/polished the mating surfaces, and beefed up the wires.
I took a beamshot, along with several other lights, didn't post them yet, and you can see the nice wide beam compared to others -- I know at least one guy who doesn't care for the pencil beam of the TN31mb - it is limiting. And the lumens you get with the XM-L2, outstanding... The reflector is really big... 
btw, JOE is the man for this XM-L2 TN31's at $135 shipped (thread on BLF), US. What's sic bout this mod is that it's very little in parts, 1 resistor ($1 at DigiKey), rest is supplies - wire, AS5, etc. Verified - drivers/star in the XML and XM-L2 versions appear identical, I could see no differences.
Edit: Also when my meter battery starts dying, the readings consistently go up and I'm think'n - wow! This mod is really hot!! Then oops, what's that little icon on the display, oh, it s a battery.... Don't know how many times I've been fooled because it starts out slowly raising the readings.... Of course I'm using rechargeable 9 volts from FT.
So yours came with the XML2 already, you just changed the driver to one that draws more amps?
No driver change, just adding a simple resistor mod I did not come up with - was published here on BLF, post #19: https://budgetlightforum.com/t/-/17637, and here: https://budgetlightforum.com/t/-/16603. All the credit to AlexGT!
I used to think the Shocker was bright… Oh how I have been mislead!
TN31 top, Shocker bottom.
Wow, that beamshot looks like the sun. I swear I see the sun flares radiating out.
Not sure if you’ve realised, but you know the pattern you see at moonlight when you shine it 2-3cm away from your table/wall? That flower pattern?
Yeah, that’s still visible from nearly 4 meters away (on 2nd level). Just goes to show that some lights (especially throwers) collimate their beam at a longer distance. Even though it shines 1.2km away, I can’t actually see that far away. But I can light up white houses 780 meters away give or take 20, that is crazy. I wonder what other people are thinking when they see the beam haze from a few hundred meters away.
If the hot spot was any smaller I don’t think it’d be much more useful, so this is definitely around the optimal lux a light should have - at least for my eyes. And I also noticed that the colour of the dedomed XML2 (1A?) is really similar to the dedomed SST90 in my Trustfire X6.
Very excited to see the beamshot compared to BTU shocker. Even more excited that I am getting one too from Tom soon!!!