It often does refer to illumination-supply on BLF, but in this case I don’t think so tbh 
Oh yeah, I didn’t notice that earlier comment, in that case it is illumination-supply.
Yes. Sorry. Already fixed my post. I was referring to post #15 :)
Ha ha, me too now 
Thank you ALL very much for answering my Q’s. I’m kinda new to all of this, so forgive my ‘ignorance’.
The confounding variables of the differences between lights are exactly why you shouldn’t rely on a single ratio derived from one measurement from one light to speak for all lights at all settings. Different lights will give you different ratios, maybe even at different brightnesses.
What I mean is that a reading of 10 for one light won’t necessarily mean another light with significantly different beam characteristics is exactly the same lumens just because it also reads 10 (although it should be close), so it isn’t an infallible measurement. I think we agree on that bit.
But as lumens are a ratio scale directly proportional to any lux readings taken, if a light is 100 lumens and reads 10 on the lux meter then a reading of 1.5 for the same light at a lower level (or one with an identical beam profile, e.g same emitter + reflector but different bin/current) will always mean 15 lumens.
Best way to use blf is jump/pounce /strike when the iron is hot
https://budgetlightforum.com/t/-/18002
Jump jump
nice little 15$ light
I've found actual numbers to be almost meaningless.
Does it do what you need or exceed your need .Almost lights I own exceed .If not grab another .
I got a lightbox to measure lumens - compared exact lights with othe BLF member's readings, tested many OTF rated lights, so we think we are pretty well calibrated, and yes, batteries, charge level, lots of things make a difference, sometimes big. Also lots of variations between lights of the same make/model.
Just finished a mod on a HD 2010 light (single 26650 cell) and was dissapointed for getting only 1,190 lumens (4.2A, XM-L2 U2), so removed the tailcap and jumpered the battery neg. to the threads of the body, wholla - 1,360 reading. The 170 lumens drop is all because of the tailcap spring, so ran a solder wick wire (copper) down the middle of the spring, re-soldered the spring down thoroughly, all around, and now with the tailcap I'm getting 1,360 lumens. It pays to be able to measure things before-after, and experiment with -- really useful. Typical xxxFire lights have very poor quality control and most significant variations are because they forgot thermal gread/epoxy, or didn't solder something right, screwed up lens or reflector, etc.
+1 You got it right.
I don’t think they’re close enough in practice. To keep this objective, take a look at data from a third party (selfbuilt):
http://www.flashlightreviews.ca/Lightbox.htm
This degree of data spread is consistent with my experience and why I use a regression formula to calculate the line of best fit for multiple readings from different lights instead of arbitrarily relying on one ratio from one light which as you can see from the graphs would be a crap-shoot.
On top of that, multiple copies of the same light can give different readings… even the same light’s output can vary depending on the battery and other conditions.
My point on brightness levels was based on an observation selfbuilt made and which my experience also confirms. That it’s best to deal with lower readings separately and as you can see from the same link, he uses two formulas. When I first saw this I thought it shouldn’t matter but in practice it does.
That’s the thing I suppose, it’s just the scale question that bothers me. I have read selfbuilt’s posts with great interest and certainly does seems to bear out empirically… But theoretically, lumens are a ratio scale, lux is a ratio scale, so there should be a directly proportional linear relationship right?
In my (admittedly limited) testing I have found that to be accurate in practice. For example my Fenix LD20 matches up with specifications at the lowest and highest levels simply by multiplying with a set number, this is the same with my drop-ins (I have lots of home made NANJG based ones) which read in proportion with what they should at low/med/high with the same simple ratio for each.
Maybe I’m missing something completely, or have something wrong in my understanding of it, but I simply can’t think any theoretical reason why lux readings would not be directly proportional to lumens on a simple linear scale.
Well, lumens is the capture of all light output from a source (flashlight), lux is a direct measurement at light hitting a surface.
Yes, but both are on a ratio scale. So if all the lumens are in the same beam profile and environment, (i.e. in the same light in the same position for a ceiling bounce test), then lux should be directly proportional to them.
Yes because 1 lux = 1 lumen/m^2 but in practice because of the light output variables I’ve already mentioned and meter limitations & accuracy, human measurement error and inconsistencies, unique lightbox or room characteristics, etc. it’s not so clean.
Are you still comfortable using one reading from one light? Because that’s in effect like basing everything on a single random point from one of selfbuilt’s graphs and if it happens to be an outlier, you’re toast.
I thought the higher than mHa the LONGER your torch lasts. Does it have anything to do with brightness? Or just runtime?