In article <4qu354$dbl@news.cc.ucf.edu>, clarke@acme.ist.ucf.edu says...

>I am investigating the use of a Teleconvertor as part
>of a visual telescope project. Bob Neuman helped
>me with info on the Vivitar Macro Convertor, but
>a 3X would really be better for this project.
>Hence I wonder if there is a quality 3X Teleconvertor available?
>The mount does not matter since it will be used in a
>custom arrangement as part of the telescope.

The old Vivitar 3X could be OK in the center with
some lenses, but even a 2X is often pushing the
limits of acceptable sharpness.
Hope This Helps