|
Coma problems
From the dimesions you quote I'd have to assume the main mirror is about F4.8, if the mirror tests out OK then I'd have to guess that the mirror is not square to the tube and/ or the focusser is not square to the tube.
Make sure the reflection of the secondary appears central to the main mirror ( put a central dot on the main mirror to help) also check the focusser is looking central to the secondary ( a bit of white paper inside the tube opposite the focusser to outline the secondary may help) with a straight edge across the focusser along the telescope axis should show an equal gap top and bottom.
Finally use a ronchi screen to check focus and it will also show mis-alignment.
Let us know how you go.
|