If it makes more sense, think of it like this. When I began trying thru-wall I simply multiplied the lux by .29 But I discovered the geometry of the light’s head affected penetration. Lights with more reflector would get a higher percentage of their light through. And vice-versa.
So a correction was needed to pinpoint the percentage that was making it through the wall. The reference point was born. Now the official way to do wall measurements requires the hole telling us the lumens, then a matching reading from the wall… aka, the two ‘reference’ numbers.
I still haven’t tried thru-wall measurements with my sphere. Honestly its been a busy couple of weeks and I’ve barely touched my sphere since I got it. But if I’m understanding you correctly then the “reference point” correction factor is based off of a lower output of the same light. So to measure a big light I set it low and read it through the hole and through the wall, then set it on turbo and read it again through the wall. Yes? So what happens if the reflector of the light I’m trying to measure won’t fit in the hole? Is there any way to measure physically large lights with this sphere? On that point, and assuming I understand correctly, if the light fits in the hole why would I not just measure it through the hole on turbo?
That’s how I understand it as well. Getting accurate numbers for lights with a larger head than the sphere has is going to be a problem. As for your last question, the short answer is that the meter gets overwhelmed. Once you exceed (I think the number is) 1000 lumens, the meter can’t give an accurate reading. So you need to attenuate the signal that is reaching the meter. By doing a through the wall reading, some of the intensity is lost and the meter can do its thing properly. In order to be sure the correction factor is, errr - correct, you do a reading on a lower mode through the hole, then through the wall on the same mode. The app then calculates the correction factor for this light and you use that to get readings for turbo.
Lazy-R-us is right. If it puts out more than about 1000 lumen, the meter is overwhelmed and will not give a reading at all. And yes, getting accurate readings from lights with heads larger than the hole is just a problem.
During the early days of the project I didn’t realize the wall measurements couldn’t just be multiplied by one number for all flashlights. It worked inside the sphere, so I assumed it would work outside. But as mentioned, I learned the percentage of light that penetrates the wall varies. The solution in the app is perfect for lights of any brightness that have a head that ALSO fits the hole. If they don’t fit the hole, you will need to get creative on your own… You can use reference numbers from a similar flashlight. Or multiply the reading by your own multiplier.
Ok yea, my way of thinking was the same as emarkd.
I saw and understand how you did the thru wall measurement with a smaller head light.
But when I tried to mimic the same procedure with a big headed high lumen light, as I was shining the light through the hole, I said to myself, wait a second, this don’t and won’t seem to accurate because not all of the flashlight’s entire head is fitting into the hole, so even though I’m shining in low mode, only 1/2 the light is going through the hole while the rest of the beams light is shining through the wall.
Pretty much all my lights are over 1000 lumens, can you make a sphere for those?
You could probably use the same sphere and just put a circle of printer paper over the meter to dull the readings.
Ok, I figured a way to do my high lumen large lights that don’t fit the hole. I’m not sure if my theory of doing this is accurate or not, but im satisfied with it.
First I took my zebra sc62 and shined it through the wall with the meter set to x10.
I got a reading of 420.
So then I took that number and added a 0 since it was set to x10. Which is now 4200.
Zebra has the sc62 rated for 1000 lumens. I’m just gonna take they word for it.
So now I just divided 1000 by 4200, and got .238.
MAGIC number from now on is .238
So now I will just take the through wall number from any of my high lumen lights multiply that with .238 and this will give me my approx lumens.
Ie…my sc62 had a through wall number of 420. Add a 0.
On calculator, I put 4220 x .238 = 999.6 lumens
For your super high lumen lights, you will set the meter to x100. And now you will add two 0’s after your through wall number.
Ie…I took a original skyray King and shined it through wall with x10 meter.
Got reading of 860. Added a 0. Now 8600 multiply that with .238 and got 2046.8 lumens.
I did the same light with meter set to x100.
Got reading of 87. Added two 0’s this time. Now 8700 multiply that with .238 and got 2070.6 lumens.
Why don’t the people that purchased the sphere try this technique to see if the numbers are somewhat accurate.
Just multiply your numbers with .238
Did you shine it through the wall on the opposite side of the hole?
I tried what you said with my DBC-03 and got 1052 on the meter, x10, 10520 x .238 = 2503.76. The only problem with that is my other light box reads over 4000 lumens.
Using the app, I put in 1246 through hole on level 2, 22 through wall on level 2 and then 10520 through wall for 3006 lumens.
My PVC trap says 4440.15 even coming last after the other testing.
Edit: FWIW, this one fits in the hole.
I think part of the problem is that as the head size changes, so does the multiplier. To be clear, I have no experience with these, but reading this thread left me with this feeling. In order to test the theory, use a couple lights that have different head sizes that DO fit in the existing hole. Take the readings as Joshk describes in his tutorial video, then see if the magic multiplier number is in the same ballpark as your .238 that you have already come up with.
lol
Hmmm… That’s more than quite a few lumens off. I think you should try my method again with maybe some more known value lights. U have any stock lights? Or maybe even try something with less lumens. Like something easy. Something with only a single emitter. This way we know what the max that single emitter can do.
Oh, and I shined the light to the left of the hole…. On the same side as the opening. The meter and bracket is on the right side
Hmmm... I wonder is it possible to get an accurate reading(with doing all the math of course) just with a one inch thick piece of styrofoam? Flashlight on one side sensor on the other?
blueb8llz, pretty sure Josh said to use the opposite side for through wall to make use of the baffles internally. The video shows spinning the ball around so the meter is physically on the opposite side in the box, then shining the light on the middle of the ball exactly opposite the plugged hole.
Perhaps if you try it that way, your .238 number will change.
Edit: Since a multiplier of .422 equals my other method of testing, I will try a few other lights to see how it compares. Stock? Huh? What’s that? 
Ok just discovered something weird, and this proves why u got that low number Dale.
I get the same low number only when using lights with those type of cute or similar optics.
I tried four different lights with those optics. Ranging from triple xpg2 and xml2.
This is odd. Something to with these no reflector optic lights causing a low lumen rating through styrophone.
No, that won’t work because the meter has a rounded half ball for the reading, and the back to a flat piece of styrophone is flat.
Yea I experienced the same thing. The reflector definitely causes a higher percentage of light to penetrate. Without the reflector the light that bounces off the white foam the first time never gets a second chance. A good reflector gives it a second, third, fourth chance to penetrate.
This is a good group conversion, I’m going to sit back and watch for a while 
So any TIR Optic would do the same thing then, like a big 50mm TIR I have in a MagLite?
I believe so. I just found two more lights with these type of optics, a total of five lights now, and they all gave lower readings.
My biggest light with this type of optics is a lumintop ps03.
And I tried redoing the test but this time shining the light on the opposite end of the sphere and got the same reading.
The sphere does a good job trapping all the light. I even shined the light right next to the meter, and still got the same number.
The only place that DOES change the number is if you shined on the crack where the two halves meet together to form the sphere. I’m assuming there’s a super tiny crack and it’s literally right across from the meter.
You guys have all the fun. :innocent:
I’m still waiting for delivery of my sphere …