Comments by "Spring Bloom" (@springbloom5940) on "Dudes Think They Can Prove Atlantis by Measuring a Vase" video.

I use the example of the 7.25" f6 newtonian reflector telescope that I handmade in the mid 90s. I hand ground the primary mirror to 1/6 wave surface accuracy. That's 1/6 of a wave of light. I did this by rubbing a slab of glass, back and forth over another slab of glass(with progressively finer grit). I then hand corrected the spherical curve into a parabola. I made the secondary mirror at 1/10 wave by lapping two pieces of glass, into an infinite radius (the technical term for 'flat'); thats about 25nm suface accuracy. Thats roughly 1/1,000,000 inch surface accuracy without a single power tool.
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13:25 I dabble in pottery and have learned almost everything I know from YouTube. My sophisticated 'verification tool' for mass producing jars and lids that fit together perfectly? Two bamboo swewers tied together in a cross. Multiple depth and width measurements with hashes marked on the vertical and horizontal stick. Of course, Ive never actually 'designed' a piece, its always just WTF ever happens, happens 🤷🏽‍♀️
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@annascott3542 Checked out books from the county library. My mailman got me interested when he saw me setting up a telescope in the yard one evening. He had made one and gave me about 10 years worth of his old astronomy magazines and some leftover supplies. My first one was a 3" f9. I silvered the mirror with supplies I got at the camera shop. That was around '87 or '88 I researched my 7" for probably a couple months. Once I actually got started, the mirror set took about a week to grind and then about 2 weeks to correct(perfect is the arch enemy of good). I sent it out to have it aluminized. While the finish is excellent, the parabolic figuring isnt great and has some annoying aberration. I keep telling myself Im going to re-grind it some day.
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@RockinRobbins13 Its a little much to get into here, but I did a 'knife edge' test. Its relatively modern, like early 1800s(?), but its basically a candle, a razorblade and a peephole. Essentially, you set up the mirror at its focal distance, illuminate it with a lightbulb or candle and look at it through a peephole half covered by a razorblade, to view interference patterns on the surface. I would assume something similar was used for the earliest optics; Ive forgotten more of this stuff than I remember. You can lookup 'Foucault knife edge' for more info. I didn't have any elaborate apparatus, just a basic optical bench.
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@MelvinCruz Your reading comprehension and or intellectual integrity, is atrocious.
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@seanlove7063 Imbecile
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