[Andrew C]

I have a Vixen Geoma 80A spotting scope, to which I would like to attach a CS mount astro video camera.

The scope body has a male M42? threaded flange over which the Vixen EP is screwed.

Superficially, it looks as though an M42 to C/CS mount adapter would do the trick for what I want to do.

The problem is that the back focus distance (flange to focal plane) of the scope body is very short, and it does not appear that the adapters (which seem from the photos to be fairly long) would allow the scope/adapter/videocamera combination to focus out to infinity.

The Vixen EP has a central section that actually fits inside the flange (presumably to keep the whole assembly compact), and this may be their proprietary solution to this issue.

Has anyone solved this one (narrow C mount teleconverter to fit inside the flange or some other solution)??