Re: [APML] Guide scope alignment

[Mark Kaye <mark.kaye@sympatico.ca>]

> I have always used an OAG, never
> a guide scope.  Just bought a Megrez 80 as a travel scope but would
> like to shoot some wide field with it using my primary scope as a guide
> scope.  Assuming proper polar alignment of the mount, is it
> necessary to precisely align the Megrez with my primary scope (which
> would be used to guide)?  The Megrez comes with some nice clamp-type
> rings and I am trying to decide whether I need to buy adjustable rings so
> as to align it.  Any help would be appreciated.

   That is one of the beauties of using a guide scope, you can
move the guide scope around to find a suitable star without compromising
the framing of the object.  In theory, if your scope was perfectly
polar aligned and you never had to do any declination corrections, you
could guide on any part of the sky and shoot any other part.  Of
course, in the real world of differential atmospheric refraction and
declination drift, it is best not to wander more than a couple of degrees
from the guide star.  That still gives you plenty of latitude to
find a good candidate.  Once you select a guide star and a photo
subject, your two assemblies must become completely rigid.  That is
where your problems are going to come.  Flexure is going to be a
larger enemy than not having the guide star centred in your
picture.

   Clear skies!
              
MK

The Observatory by the Lake
http://www3.sympatico.ca/mark.kaye/