[Chaos-l] Another idea.....pls advise

[Jim Pressley]

Michelle,
The Celestron Nexstar 130 telescope's mirror is ~5" in diameter, with a
focal length of 650 mm.   The 8" Dobsonians discussed earlier are about 1200
mm in focal length.    There will be performance differences here...almost
an apples and oranges situation...that might better be discussed and
explained in person at a club meeting.

For example, although the step between a 5" and an 8" mirror may seem
relatively small, their respective surface areas are 20 square inches
(6") and 50 square inches (8").   That equals an almost 2.5X increase
in light grasp.   In most cases, brighter is better.

It may come down to deciding which is more desirable...a 2.5X brighter
image or computer control to find objects.   Certainly, computer controlled
telescopes have merit...many of us use them...but you can enjoy learning the
sky by star hopping with a finder and star charts.  In fact, this is a great
way to learn the sky and can be a very satisfying pastime.

It might be best to simply hold off purchasing anything until you and you
son can attend an observing session and see first hand the differences in
various types of telescopes.    It's not easy to make an informed decision
without understanding the many options offered with today's modern
telescopes.

As several others have said, I too would go with aperture over features, but
everyone has to find out what they want for themselves.

Jim
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