🚀 go-pugleaf

In article 10223@linus.mitre.org, chaloux@mandolin.mitre.org (Dave Chaloux) writes:
>It is a well established result that SCTs which have moveable mirrors for
>focusing are at their best at only one point among their many possible
>positions. Since many things require the mirrors to move in order to
>focus, it is unlikely that Joe Amateur is using the mirror to its best
>capabilities. Different eyepieces, different diagonals, differences in
>distance to the object focused upon, etc. will all change the position
>of the mirror required to focus.
>
>It occurred to me that it might??? be possible to use this fact to advantage.
>Jim's Mobile now sells a focuser for SCTs that works without moving the
>mirror (What an idea!). If positions of the mirror on one side of perfect
>lead to undercorrected images and positions on the other lead to over
>corrected images you could use this to tune you telescope for no
>sperical abberation.
>
The astronomers here have a 1m telescope that uses a C8 for a finder,
and they've done just this, except that when they found the right place
for the mirror, they flooded it's cell with epoxy resin and stuck it in
place! I've never seen what this scope can do myself, but it is reputed
to be very good.


---
Andrew McGregor,
Physics, University of Canterbury, Christchurch, New Zealand.
adm@phys.canterbury.ac.nz