Quote:
Originally Posted by luka
Marcus, when you said that the scope is spec'd to 1600mm, have you got a confirmed source that it is 1600mm and not 1623mm?
To answer your other question, the adjustment of the distance between the primary and secondary (which affects the final focal length as measured by plate solving) is achieved by shifting the secondary mirror (there is a screw in the middle of the primary to shift it in/out).
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No Source, just asking the question as to what the tolerances are for the scope to vary from spec. In which case, setting to the published spec could put the scope at less than optimum performance.
Really the question is how hard is it to fashion a mirror where the focal length is accurate down to the millimeter, and do they bother or does it vary?
M