I tested my donated mirror
WOW! That’s a good mirror!
Previously, @BeasMeeply graciously donated me an 8" mirror. The problem: I don’t know what stage of mirror making I have to do.
So I talked to a local astronomy club. I got to use a spherometer to measure the curve - same curvature all around, accurate to within 0.0002 inches. I put it in a foucalt tester, and after lots of help and fiddling I got some pictures of the result! The fact that it’s transparent enough that I can see through the glass and get a result in the foucalt test tells me @BeasMeeply got through grinding and polishing, and now I can skip to making a pitch lap.
How do I interpret this? I don’t know yet. But someday I will