Texas_Ace BLF Calibrated Lumen tube / Sphere No math skills needed - Several spheres still available

So even nitecore are not true to the numbers?

I can’t seem to find the fenix I used to have, I might of given it away.

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.

Maukka, what type of sphere are you currently using? I assume it’s a high dollar professional unit?

I use a 50cm Lisun sphere.

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.

That is for your job, right? You don’t buy all your specialized equipment just for hobby use.

I’m curious why can’t we just apply a factor in the settings of the lux meter. Isn’t that how you calibrated them in the first place?

There is no calibration factor on the lux meters. The tubes are (supposed to be) physically calibrated with diffusing material so 1 lux = 1 lumen on the meter. Fixing them will require physical modification to correct the calibration.

Oic. i always thought TA modified the settings of the lux meter to apply a calibration factor.

Oh, if only it was that simple, the last month of work would of only taken about a week lol.

Each sphere had to be individually “calibrated” by changing things like what diffusing sheets, how many, what direction they pointed, adding or removing reflective tape ect. All of them were different for reasons I can not explain. Not massively different but enough to cause each one to need a unique setup.

In this case since we only want to reduce the lux on the meter and we are not worried about diffusing the beam and making it even, we can put something just over the meter that should not suffer the wide variances.

The question is what to put there. DC fix is a possible option.

Thanks a lot! I’ll redo the calculation, then fine tune the calibration# when I got time!

I cant wait to get my tube… i got many lights… my main testing with be stock lights and skylumen lights… i will be testing variety of lights, small, big, flood, and thrower.

Stock lights

Emisar d4 quad
Emisar d1s
Blf q8
Lumintop odf30
Thrunite tc20
Thrunite catapult v6
Fenix Tk35ue
Acebeam L16
Noctigon m43

Modded skylumen

Tn42vn90
Tn42vn olson
Olight x7
Mateminco mt18
Manker u21 olson
Acebeam k60
Acebeam x45
Notcigon m43

Will test more along the way…

So to reduce the amount of light hitting the sensor to re calibrate, the extra diffusing material needs to be right at the sensor? Isn’t there a diffuser plate near the front where we place the light? (I haven’t received mine yet so I haven’t seen it) Couldn’t we just add more diffusion material there?

I suppose when I get the tube (ETA Monday) it would be best to take measurements with ANSI rated lights? I have some Eagletacs I can try that have ANSI specs listed. Also is there one light that most of us own the same model we could be test to between us to compare, such as Q8?

It’s here sitting in my living room, thankfully I have an understanding wife…

Wow!! She is definitely a keeper…… :+1: … :slight_smile:

Yes, there are 3-4 diffusers in the tube actually. They lower the readings on the meter and mostly spread out the light so it is even and beam pattern does not effect the readings. This is a major problem with this design if you do not have the diffusers in place.

The problem is that even a minor change to the ones at the start of the tube can have big effects by the time it hits the meter, which is why it was so hard to calibrate them.

By putting the new one right at the sensor it should have the same effect across all the spheres.

Although naturally I will test several methods when it comes time for that.

Okay thanks for explaining.

Holy cow you cant be serious right? That thing is HUGE!

50cm is about 20 inches. So not huge. I’m sure it’s expensive, though. Plus he’s got all that spectral analysis equipment. I assumed he worked in a lab or something and used their equipment in his off time. :slight_smile:

I heard those sphere cost about $10000…