Thanx for this info. I have no idea how to get the lumen reading either. 
Are you familiar with how to integrate the area under a curve via calculus? Measuring lumens is kind of like that, except instead of measuring each point under the curve we try to flatten the curve out first then measure only one point.
The easiest way to estimate it is to do a ceiling bounce test. Shine a light at a white ceiling, put a lux meter somewhere else in the room, and read the value. Calibrate by using lights with known outputs and developing a function to convert ceiling bounce values into ANSI lumen values. It’s not very accurate, but at least it’s easy and requires very little special equipment.
The next best way is to build a large white sphere with two holes in it… one for a flashlight to point into, and one fitted tightly for a lux meter. This is similar to the ceiling bounce in that it assumes the light will be fairly evenly dispersed and only measures one point, but it’s better at dispersing the light evenly and retains more energy so there’s more to measure. This is probably as complex as almost anyone on BLF cares to attempt.
The proper way, the way we’re trying to emulate, is to measure the output at every point in the beam and add the values together. Much like measuring the height of a curve at every point and adding the values together as the width of each sample approaches zero, we’re trying to take the integral of the 3D beam pattern function. This is prohibitively expensive though, and requires lots of relatively complex hardware.
Realistically, you could probably do fairly well with a cheap lux meter, a styrofoam cooler, and a lot of calibration. Or papier mache around a beach ball. Or a milk carton. That’s how selfbuilt does it. It was based on this design.
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Whoa! 
This information will keep me ‘busy’ during off hours for a few days once I get the lux meter I ordered as I’ll be building my own light meter. I think a sphere light box distributes light better than a cube light box. The only problem would be finding a sphere styrofoam cooler. :~
I love to improvise and I’m looking forward to completing my very own light box soon.
Thank you very much ToyKeeper! :bigsmile:
http://www.smoothfoam.com/product/10073.html
The top of the inside domes has a flat spot. You can leave it as is or, even better, sand it to match the contour of the sphere.
Especially light crap.
Thank You.
im in
If I had a LUX Meter, I’d measure all my lights. I’d measure the sun on a cloudy day, I’d measure street lights and house lamps, and fluorescents and LED’s. I’d figure out a way to convert it to Lumens to compare to the manufacturer’s claims. I’d measure the output of different battery chemistries and find out just how much more intensity I’d get from 10440’s versus AAA’s, or even 14500’s vs AA’s.
Oh! :money_mouth_face:
Thanx texaspyro!
It can be usable crap, I think. I’m in, thanks!
I like crap.
Actually, most of my lights are crap too.
Why couldn’t we measure it (light) like they measure the heat in a hot pepper. Scoville units…basically it’s how many glasses of sugar water are required to quit tasting the heat. Initially it was done with LOTS of people. So we could just line people up at measured distances and test their perception of the light. We could use people waiting for a ride at Six Flags or something. 
Can you see me now? How about now? Can you still see me? How about……
Is this crap legit? Then I’m in. Thanks.
Just a little bump in the night for the stragglers… the door is closing on this giveaway rather soon…
That’s nice. I hope we can still see you in your 3333rd post!
We have a wiener… that crap lovin’ LIKEABOSS is the lucky fellow!
congrats to LIKEABOSS
Congrats to LIKEABOSS and tks to Texaspyro!
Well done LIKEABOSS and thanks to texaspyro. Cheers guys.