We just need to find a consistent, thin, film-like material that we can layer up.
A paper-based product would certainly be cheap, but I’m not sure of its consistency. I think you share the same concerns. Maybe we can test a variety of thin papers.
What about a lens that can be bought and stuck into the hole that the sensor mounts into? Kind of like a neutral density filter but fairly weak. I’ve got that ND filter you sent me and that thing really knocks down the lumens. I have to multiply my readings by 13.1. This should be more consistent, but the odds of getting exactly the right reduction in output seems a bit slim.
I will do some more experiments next week and report back.
Based on the results from fifteen lights (manufacturer spec vs TA Tube), my average correction factor would be .728
Later, if we need a standard across all units, I can also use that. But for now, that number makes the tube useful for me until everything gets sorted out.
If others can post their correction factor, it would be interesting to see if the results are close - or not.
When you say spec, do you mean the lumens the light is advertised to be?
Compared to the JoshK sphere, my numbers (roughly) are around .65 to .70, so pretty close to your .73. We are in the same ballpark. :+1: Of course, this all needs to be decided later on.
We should also try to standardize the time we measure. ANSI-FL1 says 30 seconds. That might be our standard time unless we state otherwise.
The batteries also can make a difference with certain lights. I have 26650 blue and black Liitokala’s that are low IR. I’ve also got some low IR button top 30Q. I can have several on the charger as I’m using one. Then put it on the charger and grab another so the voltage is always topped off.
I guess I will record the lumens as they come off the stock TA Tube. Then we can probably decide on a specific correction factor at a later time.
I can see this being a fun marathon session when I get a day off.
It is much higher than mine. Base on maukka’s review DATA, my average calibration# for TA’s tube is 0.6730133. The number is not 100% accurate because I know maukka did upgrade & recalibrate his integrating spheres several times.
I use most mid & low mode for more constant output from maukka’s review found on CPF and BLF. I choose seven stock lights same model & CCT as in maukka’s review to calibrate TA’s tube:
Lumintop Tool AAA Copper Nichia
Lumintop Tool AAA Ti Nichia
Zebralight SC600w HI Mk3
Olight H1 Nova NW
Olight S Mini Ti NW
Nitecore EC4SW
Nitecore MH20 NW
I wouldn’t use the Lumintop Tool AAA for any calibration as its driver has been known to vary wildly from one batch to another. I can remeasure the Nitecores when I have time to give you more accurate numbers. It was a long time ago when I tested them.
If I find time today I think I’ll try layering some DC Fix in mine, unless someone has tried it already. More diffusion, plus reduction. Might take several layers but worth a shot. The stuff is cheap, ~12 bucks a roll from amazon and I’ve got plenty of it here.
Here’s new output numbers for Nitecore EC4SW and MH20. Both with full 30Qs. Measured first on high, then on turbo, so the turbo numbers aren’t with absolutely topped off cells, since I had the high on for about 40 seconds. I did let the light cool off a couple of minutes though.
Seems my small styrofoam sphere I used when originally tested these was reading about 8-9% low. Still I think a 10% error margin is quite good for DIY integrating devices.
This is an option I was considering for a fix-all solution. Or some other similar film. Possibly cut out some acyrlic discs to fit in the hole the sensor goes and then add layers of the DC fix to it until the readings are correct. People can then install it. Although I have not figured out a good method for that yet.
While we’re all bouncing factory numbers around don’t forget that the variation among LEDs in any single flux bin is something like 12 or 15%, so Nitecore may say a light makes 1000 lumens but each light made will actually vary along a range of output depending on the efficiency of that specific LED and where it falls in that bin range. The only way that I can think of to calibrate these tubes to within less than the binning variation is to either sample many many many specimens of the same light and average them, or better yet to compare the tube’s readings against a NIST-calibrated sphere using the same exact light source, not another specimen of the same model. …which is what I tried to do using the HDS lights because supposedly they do that for each individual light sold.
Exactly what I have been preaching for years, the 14% tolerance from Cree on their LED’s inherently means you can’t get better then that without a ton of measurements.
On top of that you have the tolerances of all the components on the drivers, while 1% is common for some things 5% and even 10% is common others. Also the tolerances can compound on each other depending on how the driver is setup.
So 5-10% for the driver / rest of the light fluctuation and you can easily have a 20-25%+ variance strictly due to the tolerances of the components in the light. Then you have the environment factors, this can be seen more with throw readings at distance but it will still play a role in the tube readings. I can see a few lumen change in readings on very humid days vs dry ones.
