Okay, I’m planning to build sphere #2. I’ve picked up another (2) hollow 12” styrofoam balls identical to my first sphere. I did catch that I believe my styrofoam balls seem to have thinner walls than djozz’s (could this be part of my problem? - Perhaps why so much light seems to escape through?). Mine looks like this one.
Anyway, with this one I am looking to still have a +/- 90mm entrance hole, but this time fit a piece of glass with DC Fix attached to the underside of it into the entrance hole. Sourcing a 4” round piece of glass is more difficult than I thought it would be! I have looked into obtaining diffusion lenses used in LED recessed lighting, but that seem difficult and expensive if buying the entire light for the lens. It also seems that the 6” recessed lights frequently have a lens that is only about 3 1/2”. I did manage to pickup a clearanced recessed light which I was able to remove a 3 1/2” x 3 1/2” square diffusion lens. It is plastic, does a wonderful job of diffusing a flashlight beam into a smooth wide wall of light without any throw, but seems it would be difficult to mount and would be too small to still have a 90mm round hole. I think on this sphere I will paint the inside with white acrylic matte finish paint (after sanding the foam). I then think I will cover the outside of the sphere with brown paper and glue (got the idea reading this technical article on a cheap I.S.).
I’m unsure if I should change anything with the luxmeter. I might just start with the same setup I have now - dig out some of the wall (perhaps a bit more this time) and mount the luxmeter against it. I was also thinking to fully remove the styrofoam creating an opening for the luxmeter, but first attach a PVC pipe 90º elbow so that the light can’t directly reach the luxmeter sensor. Also thinking to maybe add DC Fix at this opening as well. I’m considering adding a baffle in front of the lux meter opening too, but not sure if it’s needed or not. Maybe I’m already changing too many things to see what the problem on the first sphere actually was!
So any thoughts on what I’m planning? Does any of this seem wrong? Djozz?
Thanks,
-Garry