Hello Paul,

> the inversion menu has an option for rotation, and I
> can sometimes see that the fov thru my 101mm refractor
> needs a rotation adjustment in Guide,

you may use the rotation angle in different ways:

- If you want to match the fov of your camera (film or ccd) exactly to a
map produced with Guide and it is not perpendicular to RA and Dec.
you have to rotate in Guide. In this mode you usually use the setting
"RA/Dec (North up)".

- The second case is the visual work at the eyepiece. Normally one
would prefer an "Inverted" view and "Alt/Az (zenith up)" here. This is
the case when you are standing or sitting behind your telescope
without a diagonal (refractor, SC telescopes) and your eyes are
parallel to the horizon. With a newtonian reflector you have to choose
"Mirror image E/W".

Every time your eyes are not parallel to the horizon in this mode you
have to use "Rotaion" to accomodate this. When looking south there
should be the least problems. But when look to the east or west at high
declinations it is sometimes difficult to keep your eyes parallel to the
horizon.

I hope this clarifies the situation a bit.

Clear skies
Bernd


Bernd Brinkmann
Herne, Germany

http://homepage.ruhr-uni-bochum.de/Bernd.A.Brinkmann/index.html