Expert: Tom Whiting - 7/14/2005

Question
I'm re-immersing into my childhood hobby in my retirement years, and am kind of new at scope shopping; I hope you can help. I want more than a beginner scope, and all types have their own kind of intrigue. But as to refractors: the cost of a good-aperture APO (say, 4" minimum - with driven mount) is kind of prohibitive. But a regular achromatic is easily affordable. Isn't there a filter or some way of eliminating the chromatic aberration? If not, I'll be going with a driven Newtonian or CAT.

Thanks,
Tom Griffin
San ANtonio, TX

Answer
Hi Tom,
Sorry, but I never received your original question....and then my first thought upon Allexperts notifying me...was that I can't help you because I know nothing about refractors; never owned one as all my scopes have been large aperture Newtonian Reflectors.
But then I got to thinking, why do you want a refractor
anyway?  What do you want to specialize in? ...is the question you have to ask yourself.

Deep Sky Objects? Lunar/Planetary detail? Comet hunting?
Variable stars? Splitting Doubles/Multiple stars? asteroid
hunting? Nova hunting? Comet Hunting?  Etc. etc.

Scopes are like airplanes; all airplanes fly  but you don't
send a bomber to do a fighter's job.  So you want to determine your specialty...your very favorite astronomical activity first, then get a scope that maximizes that activity.
(Otherwise we'd all have the exact same scope, wouldn't
we?  But we don't, for reasons above.)
Long focal length refractors are mainly good for lunar/
planetary details and splitting close doubles.  But they
are not real good on the other activities listed above.

So first determine your primary activity, then get a scope
most suitable to that need.  Also, you might be advised
to first join a local astronomy club (I'm sure a big city like
San Antonio has one)....join in on their observing sessions...
see what the others' use, and learn, and go from there, and
see what the other club members advise you.
Clear Skies,
Tom Whiting
Erie, PA
Pres...ECMOG