I tried posting this on sci.astro and got no replies. Maybe this is a better place to ask.
Books on amateur telescope making emphasize that machining lenses and mirrors is prone to produce astigmatism, whereas hand grinding lenses and mirrors tends to randomize errors and thereby avoid stigmatism. On the other hand, I haven't heard any complaints about astigmatism in commercially ground lenses and mirrors, and I doubt very much that they are ground by hand.
So, what I would like to know is this: what are the machines and processes used by commercial manufacturers of telescopes and what book explains them in detail?
Ignorantly, Allan Adler snipped-for-privacy@zurich.ai.mit.edu
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