Dale, your brain is tuned to a whole nother channel 
Do you scream “ITS ALIVE!” When you light that beast off?
What? Is that unrealistic for the 12” Sphere?
<—- tossing lights around, I know there’s one in here somewhere that still carries ANSI ratings, maybe a Nitecore? Like the EC4? It should be well regulated, running 2 18650’s to a single XM-L2… maybe a stock X6? It’s running an 7135 chip driver so again, decently regulated but not the same as the Nitecore. MecArmy PT14? PT10? Pretty sure they’re regulated. My PT16 doesn’t qualify. 
Maybe I have a light coming that will qualify, pretty sure there’s a couple on the way… TR20? Cu Tool? (not many here that haven’t had, um, surgery…)
What is that streaking in from the right? A moth? Icarus?
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sumdumbug, they are always on kamikaze missions seemingly. This one seems to have crashed into the ground and exploded in a blaze of glory huh? LOL
The spheres arrived! I am doing some calculations and building jigs. There’s going to be lots of geometry involved. I will post pictures of #1 later today when it’s ready!
The hole will be angled with a 2.25” minimum, as suggested by members earlier. The angle of the hole will allow for slightly larger flashlights to also get into position. As well as keep the plug from falling inside if you do the through-wall method.
Sweet!
So, curious, doesn’t really matter either way but am wondering… I built a Trustfire TR-J20 today that makes 11,419 lumens, that’s 33,100 on my meter in my box with a .345 multiplier. The head on this light is 3 5/8” across. Will something like this be measurable in this sphere?
If the beam is less than 2.25” you have two ways of measuring it. If the beam is too large for the hole, then you could measure it through-wall.
The dilemma is that a hole that is 4” for big lights leaks so much for small lights… however I could try making concentric rings, but good execution is far harder.
That’s ok, the monster lights are not as common so it might be good to not worry about them for this project. 
I was just wondering if I’d be able to get sort of a confirmation against my PVC “P” Trap light box.
I will experiment more, but I have high hopes that the through-wall method will be highly reliable. I believe so because the color of the light does not change as it shines through, and the interior is lit the exact same with either method. Just reduced brightness when through-wall. Which is also good.
Another thing that might bring some comfort before the through-wall results, the meter itself has a plastic half-sphere over the sensor itself, so the meter is designed with a through-wall method built in.
True enough, a diffusion dome is on the meter. Essentially the same concept. Reduce and re-calculate.
Wow. I have 1 sphere built with a 2.25” hole. The BLF A6 has a 0.93” head.
If I measure it @ 112.5 lumen, I get a lux reading of 15600. But if I cut a styrofoam skirt for it, the reading climbs to 20500! I confirmed by switching back and forth many times. Same result. That’s about a 30% loss through the hole!
Will there be a platform that our lights rest on when doing the tests?
And what is this thru wall method that you are talking about. I’m glad there’s a alternative to measuring lights with larger heads because I got quite a few,and to be honest, I care more about the readings to large head lights because most if not all, gets modified. Why not right? Big head means big thrower or multiple emitters for big lumens.
So not everyone does the exact same mods so it’s good to have a place to measure these monster lights hehe
I know it sounds good, but there won’t be a platform for 3 big reasons…
- most lights are so heavy compared to the sphere there’s no decent way to prevent tipping/crashing.
- a flat platform does not properly aim many flashlights, even if it jacks up and down. You need the beam horizontal.
- you really should not leave the light in the sphere between readings because heat build-up is bad for the flashlight and sphere. It should be lay beside the sphere between readings.
The through-wall is simply firing the flashlight at the opposite side of the sphere from the outside. The light makes the styrofoam glow like crazy.
Of course, there’s nothing saying you can’t make a platform for it.
Alright, so as mentioned we lose 30% light out the 2.25” hole with the A6 flashlight. Using a bonded-foil disc I was able to reduce that loss to 4%. It seems I can’t get below that because of the light-pipe effect the 1” foam has going on. I did some research and could not find any flashlight that would fit in a 2.25” hole but not a 2” hole. Even a small reduction in diameter gains significant surface area.
So the proposed solution is to use a 2” hole and provide bonded-foil discs to select from for a better seal. This relies on the thru-wall method for larger lights. I am pleased to say the thru-wall testing is going better than expected, the readings are more stable and repeatable than thru-hole readings.
Anyone have alternative solutions?
I strongly considered my concentric-ring idea, but I imagine the foam rings would be hard to keep in place and too delicate for a durable product.
Just wondering aloud (on my first coffee at that) why we can’t make out own adapter rings from flat styrofoam, flush with the end of the light or with the head projecting inside by the wall thickness of the sphere, then hold that against the opening? Foil would change the reflection factor and be less consistent. And what about the adapters changing the interior surface area, would that change calibration? I’m thinking that I read where the interior surface area should remain constant somewhere but I don’t trust me without more coffee this early in the morning!
Phil
Yea, if you found some similar styrofoam and didn’t mind making one for each.
I kinda thought the AL foil was a good mimic of a flashlight face. When you use a larger flashlight, you are replacing foam with reflector. So it might actually be good for consistency to be keeping the reflective patch the same size.
Good point there Josh- you’re probably on the right track with that.
See what a lack of coffee does to me? :person_facepalming:
Phil