Interesting.. I still have 10" f/5.6 Coulter Optical mirror that I bought it in USA back in '80-ies.. and it is still OK, after 5~6 washing and an accident (when the tube slipped out of my hands and hit the concrete pavement, resulting in secondary hit the primary and damaged the coating.. if not for that, it would have been perfect), even after so many years.
Even like it is now, it is quite good (IMO).
Looks like they do not do things like they used to in the good old days...
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