I don’t really understand the concepts behind an integrating sphere, I wish there were an affordable one just because I’d like to test my mods. This would certainly be reflective, but aside from putting a hole in it ruining the structural integrity/shape I assume there are many other reasons it wouldn’t work that I’m unaware of. https://www.amazon.com/TONIFUL-Hangable-Aluminum-Metallic-Decoration/dp/B07X655671
Seems like there is a decent market for this and data logging light meters, I’m mildly surprised we don’t see some package deal priced well out of China.
If you are willing to pay loads of money for shipping from EU, you can get a 50 CM (around 20”) eps ball that makes a fantastic sphere. They’re about $40 US, but shipping will easily be that much. That will handle reflectors up tp 110 mm and many tens of thousands of lumens. I have a 30 cm one I use for testing and it’s great. You need a calibrated light or one of verified outout to set the multiplier for getting your relative lumen values, but once calibrated, you can get very close (5-10%) to the actual output. Djozz has a great tutorial for it on here to where you don’t need a baffle, ND filter or diffuser…you measure the light through the wall of the sphere and that works. Mine is only good for reflectors up to 65mm, so I built a lumen tube. Point is, there are options for integrating devices that don’t cost hundreds or thousands of dollars.
I see people referencing calibrations. I am sure it would take me a long time to catch up on the people and their methods, but would a sphere like that get me at least 5% precision?
If under a couple hundred total cost, time tweaking and learning is my concern, though I can totally see enjoying that process.
It’s worth it in the long run. It took me probably 10 flashlights (including a loaned Makkua calibration light) and several hours of work to get my multiplier/calibration right. You need to test different sizes and types of reflectors, flooders, throwers, different tints and cri to get it dialed in. I found Fenix, Thrunite, and Olight are good samples to test your calibration with since they use constant current drivers for consistency and their factory numbers are pretty trustworthy. I think 5% is a bit far out, but not impossible. Generally, 10% is considered acceptable and totally realistic. Just be patient and take your time, have fun with it.
I did find that thread and even asked if TA might build another. The Ace named a decent price for sure, but I said I would pass (for now). He need not wonder, while I learn enough to know what I need.
there is a vitamin jar lid over the sensor. I calibrated it by adding a couple pieces of printer paper and kleenex, until my meter read, what I though the output of the light I put on it was supposed to be, per manufacturer.
at the time I use a light called a Lumintop AAA Copper Tool, that had a 0.8 lumen low, and I calibrated to that.
later I got an HDS, which is supposedly calibrated to 200 lumens. My meter said 210 lumens, so I added a bit more tissue paper, and viola, bobs your uncle
example of using the light meter to check for output fluctuations (regulation):
1) I drilled the sphere creating two windows for input and output.
2) I painted the inside with the polystyrene primer.
The primer dries very quickly, after 3 hours I gave the second coat. It's yellowish and doesn't cover much but it's necessary to create a stable base to paint on. I also made some withe cardboard baffles, but I have to choose the right size, I'll do some tests later.
