Match's Mods: Homemade Integrating Sphere

[sixty545]

@Match

@suri252001

It was Great!!!!!! But could you let me know making out Lumen from the Lux measured ?

Thanks!

There's a quite complex formula that takes the area in sq feet inside the IS and extrapolates a lumen rating from the lux measured, while taking in the refraction and absorption of the sphere coating itself.... :Sp

Me? I cheated and just took a light with a known lumen value to determine what my sphere correction value should be.

For example.... A test light is known to give out 200lm. When you shine it in your sphere you get 2,530 lux. Dividing the lux by the lumens gives 12.65. This is the correction value (for this example).

Then, all you need to do is divide any lux readings from your sphere by this set correction value to give you the lumen output.

Hope that makes sense.

In fact the math is quite simple:

Hit the hole in the sphere with a uniform beam of parallel light (e.g. a throwers hot spot at several (5-10) meters distance).

Measure the intensity just in front of the hole with a luxmeter.

(This number is lumens pr. square meter that hits into the sphere.)

Multiply with the hole's area in sq.meters and the result is the lumens number that enter the sphere - simple and easy.

The only difficulty I can see here is the sagging intensity from the thrower, when you remove the outer luxmeter and read the one build into the sphere the light might have dropped a little. Just repeat the procedure a couple of times and you will get corresponding values.