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

I am happy with mine… if you want better result, here is an option…

Get another lux meter, and calibrate light ( tested by integrating sphere).

Whatever lumen / lux number = correction factor

Then you will multiply that by lux number.

Right now I am gathering data and waiting to get some “standard lights” to get more data.

Once I have the lights and enough data to feel that the readings are within reason, I will announce an “official” correction factor. People can use this correction factor or possibly make their own correction material.

Although Ideally I would like to find an inexpensive option that will get everyone to the right level that I can mail out. Everyone installs it and then they all read the same.

I am going to cut out some acrylic next time I am near the laser cutter and start testing options.

For now, readings with the spheres as they are would be great so I can get more data to base the correction factor on.

I must say I’m dissapointed in the discrepancies, especially considering the selling point being a calibrated tube with “no math needed”. The main advantage of this was because it was sold as a calibrated tube, which I assumed meant to lights of known values.

I’m waiting to see where the effort goes in rectifying this but getting a bunch of numbers from a variety of testers and lights with stated outputs of unknown accuracy, then averaging the numbers does not instill confidence.

I commend everyone in this thread for helping and trying to get this resolved but it should be said that the product sold was not the product delivered.

Texas Ace excels in all he does and a minor burp will not tarnish all the great work he has done for BLF members. Those wanting a lumen tube would have paid close to what he did for the materials alone. The small price he charges for his work and attention to detail in no way detracts from the value of his products.

That being said, I am sure he will fix what needs fixing and everyone will be pleased with the results (as usual).

$100 for a device to measure lumens that is close to an actual integrating sphere that costs thousands of dollars is a bargain, even with the extra TLC that will be needed.

Measuring something as ephemeral as light is like trying to measure a cup of water in steam form with a garbage bag. Congrats to him for coming up with a compact and inexpensive solution.

+1

I am highly disappointed as well. I never would guessed that the numbers would be this far off or I would never of sold them. I simply never had a good standard to calibrate them by.

Virtually every sphere you see on the internet was calibrated in much the same way, they measured a bunch of lights and averaged the results. As you can see, this is far far from perfect.

Not to worry though, I am still working on a fix, worst case you are welcome to send it back and I will recalibrate it personally once I have a better standard. Although I hope to be able to mail out a fix you can install yourself.

I am going to get getting some properly measured lights to calibrate the spheres going forward and get a good correction factor.

Until that happens you can try a plastic bag or just multiply the readings by .7 to get close.

I am far from done with this project, just nothing I can do until I get some measured lights. All the domestic options I have found want between $250 - $400 to measure a light.

I am also considering selling “standard lights” once I have a calibration I trust. Basically find a consistent light, measure it and then sell it for others to calibrate DIY spheres.

The biggest factor for these spheres is that they are consistent. I have not heard anyone complain about the consistency. As long as they are consistent it is just a matter of adjusting the numbers to read correctly. Consistency is the hardest part.

Adjusting the numbers is just time consuming to find the right materials.

Unfortunately I can’t get access to the integration spheres here at my university, only researchers in that department can sue them :frowning:
Maybe I’ll just buy my own in a few years, they seem to only cost a few thousand dollars.

You mean have it calibrated by someone with an integrating sphere? I would have jumped on that, however . . .

I just ordered an HDS Systems EDC Executive flashlight (200lm) that will arrive tomorrow, calibrated with a "SphereOptics NIST-tracable spectrographic system", according to HDS. I'll post results.

My wallet is deep into this now.

I got a good chuckle on the typo

I tested my tn42 olson thrower and deerelight xs aspheric light… the number are similiar to skylumen… i am going to fully charged the 18650 and get the final number…

Interesting, be sure to post the results. The more data the better.

Yes, I am thinking a much cheaper version of that, something like a 7135 based light (which have proved to be pretty darn consistent, particularly at lower modes).

I measure it and then sell it with all the specs for others to calibrate their own spheres.

Sounds good, keep us posted!

I think there is only one discrepancy, which is that there IS some math needed, but only for the moment. This can be fixed, it just just takes a bit of time.

No one is doing or suggesting this.

All of these tubes ARE calibrated to each other. So once we get an accurate correction factor we will be getting back to fairly accurate lumen numbers (meaning plus or minus 5%).

Then it will be relatively easy to get the tube back to reading accurately with no math. It’s really not that big a deal as far as I’m concerned. I was hoping I could get accurate numbers right now, but it seems I will have to wait a bit longer.

Just for perspective, check out the cost and work involved in using a proper integrating sphere by this company that tests their bike lights. It’s pretty crazy (and crazy expensive).

The tubes that TA is making is, without a doubt, a true bargain. Especially when you consider how consistent it is with both floody and throwy lights and how simple, fast and easy it is to use compared to a professional sphere.

Tn42vn90 skylumen 5000 lumen
TA lumen. 5000 lumen

Deerelight xsvn. Skylumen 250 lumen
TA lumen. 230 lumen

Tn42vn olson. Skylumen 700-850 lumen
TA lumen. 848 lumen

All the measurement are fresh off charger and 30 seconds…

I hope the above commenters don’t mind if I don’t respond to their claims that since it is a relatively low cost item we should not expect it to be accurate.

TA, regarding your response, I appreciate it. I intend to wait a bit to see how this progresses. I have a few HDS calibrated lights as do other’s in this thread, our readings are fairly close (to each other, not to reality), about 38% off from HDS published numbers for my tube personally.

Do we know what Vinh used to get those numbers? I seem to remember him describing a $25 lux-meter at one point.

If we’re not working with calibrated equipment like HDS’ or Maukka’s everything else is just the blind leading the blind and pretty close to an educated guess at best.

To be honest I am impressed and quite happy with the consistency, that proves the concept is solid, it just needs proper calibration. Thus far is appears that my +/-5% goal is holding up to the real world.

Now I just need to get the calibration right.

I don’t know what skylumen use… i am going to retest more lights again with the fully charged 18650/26650.,

Probably acebeam L16, lumintop odf30, thrunite tc20, fenix tk35ue, blf gt, and fenix tk15. I will try to use manufacture cells. So that’s way it is fair…,

Are the “TA Lumens” you post here from the TA Lumen Tube exactly as you received it? No correction factor or additional plastic or wax paper over the sensor??

If so…. it seems to raise more questions as to any applicable possible correction factor and/or the accuracy of the stated lumens of the lights mentioned by their makers or modders.

Why are your measurements so low? Are you using a correction factor, if so, what number?

For you to get around 5000 lumen, your TA tube would need to be reading about 6750 lumen. Is that what your getting?

I don’t recall anyone saying this, much less two or more. Did I miss something? I’m pretty sure I would have noticed if this was said.