Robert Provin said:
Hi All,
Any one out there know if the Orion ST80 and the Orion 80mm ED share the same tube diameter? Or could one interchange focusers between these two scopes?
TIA,
Robert
Robert:
The ED-80 was built on the Astroview 100mm F/6 tube and so uses the 100mm tube rings and tube diameter of with the Orion ED-100 and the Celestron C-4R scopes. I believe the 120mm scopes also use this same focuser but with an adapter.
So what that means is that the Orion ED-80/Ed-100 Crayford is a drop-in replacements for the 100mm Achromats but not for the scopes like the ST-80 which use 90mm tube rings.
The various 80mm like the WO scopes use 90mm tube rings but they use threaded focusers rather than screw on so that would be a problem too.
My thinking is that the ST-80's are good for what they are but upgrading to a better focuser is not worthwhile given the other choices out there. Used ED-80s are around $300 and sometimes the old Nighthawks are around $200. And sometimes one can find an WO 80mm Achromat or "Semi-ED=Achromat" for a price near that of a nice focuser for the ST-80...
That's my understanding...
Jon
