Among others, I own a not so recent Meade SCT, precisely a 10" Meade Basic Model 2120 (basic model was provided with “basic” mirror coating; a coating upgrade was a very expensive option…).
At that time I did not consider mirror’s shape precision at all. However, since today lambda fractions precision are the norm, I became curious to know something about my 2120.
Two years ago I also wrote to a disappearing Meade, but they did not even reply…
So my question is the following: does anyone know something about mirror precision manufacturing of old SCTs, Meade in particular?
So that would be a LX6? If so it was made between 89 and 91 and should be F6.3. There is a Meade users group on Facebook, someone there might be able to help you or maybe check out Uncle Rods Astro Blog, he is into Meade in a big way.
Meade has always claimed that their mirrors are “diffraction limited”. You can look up the definition. You won’t find anyone from Meade telling you if the mirrors are 1/20th wave or 1/10th wave. They did not measure them like that. But instead preferred to define their optics as diffraction limited. You would have to test and measure your mirror yourself, or through a lab, to know its precision.
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It’s a 20" SCT LX5 f/10.
Why worry ?
The mirrors and corrector plates on those were precision ground and matched in Irvine , California and unless it’s suffering from loss of silvering it was no doubt of the best production Schmidt Cassegrain optical tubes ever made . A true classic .