Match's Mods: Homemade Integrating Sphere

Interesting discussion over on this thread about if a I.S. is even necessary. Linked to there to save it for posterity :)

Wow, to use cut down and use a large globe is a brilliant idea. Has anyone tried it ??????? ............ Knobby

Will work.

Sixty545 built his from two lampshades. And he used to make measurement equipment for a living.

A beach ball is cheaper...

Here’s a bump for the Xsphere.

I took an inflatable beach ball that was advertised at 24 inches across, imagine my surprise when it was actually nineteen !!!

With the vinyl being so thin, I chose to not prepare the surface for removal, as it will be a far smoother surface than I could make with paper mache.

I used Elmer’s Glue-All for the adhesive, and went to town with a bunch of newspapers from the kindling pile.

I could have made the entire thing from dollar bills, and it would STILL have been cheaper than a lab-grade sphere…

Here it is, drying after a round of paint, and a taped-up circumferential cut. I will need to carve out the light and sensor ports when the meter arrives. Barium sulfate is also en route, so we’ll see how that stuff works out.

Looking really good, ChicagoX! Did you already mount the baffle on the inside? Reason I ask is because it might be hard to line up the sensor/flashlight holes and baffle with the sphere already together.

Another thing I was thinking: If you’re interested I could make a regulated drop-in with a known output to mail to you…

In fact, that may not be a bad idea to do and use it as a pass-around with the rest of the folks who’ve done this or something similar. That way we’d all be on the same page.

Barium sulfate?

I’ve been considering building one of these as well, a known output sample is insanely necessary!
What is the sample?

Dunno…haven’t built it yet :wink:
I’m thinking something along the lines of a P-60 drop-in. An XM-L with a floody lens would be ideal, since it would really test the “integrating” of the sphere.

How do you know the exact lumen output though, this is the problem i’ve been thinking about, there are no markings on an xml saying which bin it is (we have to trust what we buy is correct), and even in the same bin there is a minimum luminous flux.

That’s a very generous offer - I would very much like that, thanks !!!

I have not mounted the baffle nor made the final cuts, as I don’t have the dedicated meter in-hand. I made an off-axis circumferential cut in relation to the valve hole to allow for 90-degree placement of the two openings, and resealed it with a single layer of masking tape prior to putting on the first coats of paint. It will take but a small pass with an exacto to rend the sphere in twain for baffling and barium sulfate coating.

It’s the same stuff that you ingest in the chalky milkshakes (or enemas) to provide contrast in G.I. tract radiology scans.

It is also used to provide a fantastic diffusion coating for integrating spheres, minimizing any favoritism of throwers over floody torches.

I think you may be a bit confused. What I intend on doing is piecing together a drop-in (spec's aren't that important), and then testing it in my I.S. and obtaining the numbers for it that way, then passing it along. It's a rather crude way to calibrate I.S.'s, but really the only practical way... It will also ensure that my future lumen numbers match ChicagoX's and anyone else who would like to use the calibration drop-in.

i understand

I used a light with known consistent output, my sc60, to calibrate mine. After that I tested against others like my Ti to confirm it is consistent and accurate. I don’t know about a home made drop in with so many variables. Sounds sketchy to me. I know mine is accurate. If you don’t already have an ANSI rated light, borrow one from someone nearby or buy one.

I have several ANSI-rated lights, but I like the idea of having more comparative samples.

It’s also a great excuse to buy a Zebralight…

I think the drop-in is a good idea. I think I am pretty accurate with the lights i have to test but it would be a good comparison. Another reference point. Sphere is looking good X.

JohnnyMac, Langcjl hopefully makes my point a little more clearer. If there's a bunch of us with I.S.'s, it would be nice to have one light or drop-in to use as a reference that we can pass around. As far as a homemade drop-in with so many variables, as long as it's current regulated it won't matter in the slightest. The drop-in lumen rating won't be calculated off of any data sheet, but rather in my I.S. then passed on.

I thought my explanation to Bort was clear on this intent...but hopefully this helped a little more.

Meh... NURSE! WHERE ARE MY PILLS?!?!

Would you have to qualify which light the drop in was used in, such as a single 18650 light, versus a 3AA light, or a 26650 light? Or which exact batteries were used? I hear “regulated”, but I’m still wondering what would happen if a battery that was marginal in amperage or voltage wouldn’t mess up the test?

I’d love to make one of these spheres, but I just can’t justify the money for lights I’m going to get rid of anyhow. :frowning:

From a pure marketing standpoint, I don’t see how you can’t justify making one.

Nudge, nudge.

For all you intelligent guys out there, this might help with using Barium sulphate or Potassium sulphate coatings in a sphere.

It's all way beyond me, but it looked good, LOL.

EDIT:

Also, here's a recipe for making a stronger paste, for paper mache'

and here's where to get the "resin glue".

You know, if I've gone this far.......