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This may or may not indicate a problem.
Do this:
place a round piece of cardboard over the top of the secondary such that it is a 33% obstruction by diameter
focus to a tight point
note the position of the focuser knob
turn it inside focus until the central black spot starts to appear
Note position of focuser knob
turn focuser to outside focus until central black spot starts to appear
Note position of focuser knob
if the distance inside focus from focus point, and outside focus from focus point, are in a ratio of 1:2 or less, then the scope is ok, if more than 1:2 then it is likely the scope has optics that are not OK.
this is a "quick and dirty" test for 1/4 wave front optics.
cheers
Gary
PS the scope should be coole before you test, and not in a place where temperature is fluctuating. Nice scopes can give poor results when being tested at night and the ambient temp is dropping, so make sure it has stabilized.
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