Match's Mods: Homemade Integrating Sphere

No such thing as “too big” :smiley:

Thanks for the practical input, I am too going to build an IS (yay!), so this helps knowing how fixed I need to be on small details (not apparantly).

When I first got my sphere, I did not sand down the flat spots to make them spherical (I put the 4” diameter light port where one half of the sphere had the flat spot and the hole pretty much took up the whole flat area). The sphere still worked rather well with the flat spot on the other side of the sphere where the light hit it square on. There was maybe a 5% improvement in directional sensitivity after I sanded the flats down to a spherical radius.

My sphere sits on my kitchen floor and the room is lit by around 2500-10,000 lumens of room lighting. I have not opaqued the outside of the sphere. It works just fine and the room lighting does not appreciably affect the readings… unless you are trying to measure a small/dim light. I get around 1-2 lumens of room light leaking into the sphere. For dime lights I wait until night and turn off the room lights or just have my system subtract the background light level reading. (For color temperature testing of dim lights I use the darkened room).

heres a bump for this thread - I am currently on layer #4 of this giant glue ball of lumens :slight_smile:

For the US/UK users I see most people use Lux. 1 FC x 10.76 = 1 Lux. Other than way bigger numbers while using Lux, any reason not to use Foot Candles?

For whatever reason my 14.5” IS/Meter combo uses in LUX:10.40697674418605. The correction for 172/1790. After looking at the correction number for my (only) ANSI/NEMA FL-1 certified light of 172 lumens, I switched to FC on my meter. Basically same readings but now can use direct readout. I understand if I change meter or repaint sphere, everything changes.

I see that many others got correction numbers from 7.xxx to 12.xxx, so while fun, I would need to send IS, meter and light to BLF laboratories, INC? I like the suggestion to buy a few more calibration lights, so will continue to enjoy using the IS.

Going to build one of these! :smiley: Thanks Match!

Welcome to the ball-of-light measuring group. :slight_smile:

What is the dome made of?

Bort, you look different, did you cut your hair?

The sphere top and bottom halves were originally two large round thermoplastic salad bowls.

I did, about a month ago

I also recently shaved, have considered selling a few lights, and started a new health regimen

i think you could make more of your spheres and sell them for profit :slight_smile:

The one i built above took a bit of time to build, not sure if there is any profit in it for the time and parts used.
I have it calibrated very well now though.

But you can undercut professional model prices by a huge margin, perhaps by more then 90% :wink:

This would not likely be close to as accurate to a professional “laboratory” Integrated sphere.

Of course, but since we like budget, a reproducible integrating sphere will suffice just like a Convoy will suffice vs a surefire :smiley:

I think you should create a build thread for your device, i am curious where you got those salad bowls

I thought it did, but realized that i never did a build thread on it yet.

Nice work DBSAR! It looks very handy with all the mounting options around it.

The accurateness of professional spheres has much less to do with the actual sphere, much more with the better measuring equipment and calibrated sources, a home made sphere like we make already has excellent integrating properties.

Good point. for most of us the only way to “calibrate” our Integrating Spheres is calculations based on testing our stock known ANSI measured Lights, in my case is a few fenixes, Nitecores, Olights, thrunites, etc.

Modding flashlights to advanced for me but messing with papier maché I am in!