How hard is it to grind a mirror to exact Focal Length?
Any instrument makers out there?
I wonder how hard it is to grind a mirror to an exact focal length?
I'm curious because I have an RC scope where the primary-secondary spacing is critical (to the mm).
If I platesolve an image to derive the focal length, do I adjust the mirror spacing to put it in line with the specs? Or do I assume that there is some variability in mirror production and this is normal as long as images are good? Or that the platesolver is approximate, not exact?
Best
Markus
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