I am not looking for someone to tell me that my child's Astroscan
won't do the job- I already know that it does what it is supposed to.
What I am looking for is someone who can give me an explanation of the

Hi:

Depends on your expectations. Yes, you can get to 100x. At this magnification,
you should be able to detect Mars South Polar Cap (much smaller now than it was
earlier) and some hints of markings.

Why doesn't the Ascan do well with high power? Several reasons. This is a short
focal length f/4 primary mirror. This is more difficult to make well than a
higher focal ratio one. In my experience, most Astroscans have optics that
range in quality from poor to fair. Also, at this focal ratio, collimation is
critical. Unfortunately, the Astroscan's collimation can't be adjusted by the
user. I don't believe that I've EVER seen one that's been exactly in
collimation. Finally, the focuser on the Astroscan is poor and rather
frustrating to use at high powers.

But, hey!--if you don't expect too much, you can have some fun with this scope
on Mars, though it's far better in its role as a wide-angle rich-field
instrument. By way of comparison, the ubiquitous 80mm f/5 refractors do
considerably better on the planets than the Ascan...


Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
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