[vsnet-chat 212] Re:

[Fraser Farrell <fraserf@dove.net.au>]

On 1997-03-28 therese.jansson@swipnet.se said:
   >I am what you can call a beginner on this astronomy-thing. I am
   >thinking of
   >getting a telescope and now I am woundering if any of you who has
   >some experience can recomend what I should buy.

Buying a telescope is like buying a car; because both can be expensive,
there are different types for different tasks, and if you get one of
poor quality it will only disappoint you. Like cars, each type of
telescope has its devotees and its critics, and some types are better
for certain tasks.

However, the telescope despised by all experienced observers is the
Department Store Telescope.  These pieces of junk are typically found in
larger shops, somewhere between the camera department and the toy
department; and are easily recognized by the outrageous lies printed on
the packaging.  Such as: "magnify up to 900x", "see millions of km into
space", or "see spiral galaxies and nebulae" (implying that you will see
as much detail as the Palomar Observatory photos on the box).

What they don't mention is that the 900x image will be a useless blur
(assuming the telescope stops wobbling for long enough), that most of us
can see things thousands of lightyears away with the naked eye, and that
professional photos go much fainter than the eye can see.  Furthermore,
the optical quality of most of these wallet-slimmers is questionable.

There are only three things you can use a Department Store Telescope
for: (1) as a finder on a real telescope, (2) a coat-hanger, or (3) to
support tomato bushes.  Enough said...


As for buying a real telescope, here's my advice:

I would first ask "what do I want to do with my telescope?"  For
example, if you want to see typical galaxies and globular clusters as
more than fuzzy blobs, you will need at least 20-25cm aperture.  If you
just want to look at the Moon, a smaller telescope will be OK.  If you
want to search for comets, a telescope with a large field of view is
better.  Do not attempt any telescope astrophotography or CCD imaging
until you have had several hundred hours of observing experience.
Getting good pictures is not simple.  Be a visual observer first.

A most important factor in a telescope's capability is its aperture -
the diameter of the primary mirror (reflector) or objective lens
(refractor).  A bigger aperture collects more light, which allows you to
see fainter objects and more detail.  Refractors become very expensive
above 10cm aperture, which is why bigger telescopes are usually all
reflectors.  Good reflectors smaller than 10cm are difficult to make.
And you guessed it, the bigger the aperture, the bigger the price!

So your next question is "how much money can I spend?"  Be realistic; a
fabulous telescope will be no fun if you go deeply into debt. If your
money is limited, consider buying a good set of binoculars on a tripod,
or making your own telescope.  My first purchase was 7x50 binoculars and
I am still using them 27 years later for bright comets and variable
stars.

BEFORE you spend any money, try looking through several telescopes at
various objects in the sky.  A "test drive" will tell you much more about
telescope capabilities than all the advertising in the magazines. Do you
have a local astronomy club?  Do they have viewing nights?

If you are buying something from a magazine, read the fine print.  A
common trick is to show a picture of the fully-featured model, and print
the price for the no-features model!  Be careful.  Another problem is
that "foreign buyers" often have no warranty protection, so try to buy
from a dealer in your country.  Your local astronomy club may have
someone who will make you a telescope, or know of some reliable
telescope dealers.

You do _not_ need to buy the Ultimate Telescope immediately.  Buy
something simple, use it for a few years, then consider upgrading.  By
then you will have a much better idea of what you want, rather like
buying your second or third car.

A 15-25cm telescope (eg: Dobsonian reflector) is a good starting size
for several reasons:  it will fit into the average car (if you observe
away from home), you can carry it unaided, you don't need a ladder to
reach the eyepiece; and it will show quite a lot.  Avoid having lots of
clever gadgets, because the best telescope is one that is easy to use.
As a beginner you will have enough to do without wondering which of 237
controls to use next....

A good observer can do great work with a simple telescope, but a fool
can do nothing useful with _any_ telescope.  For example, Bill Bradfield
discovered all 17 of his comets with homemade telescopes.  Most variable
star observers in Australia use non-computerised telescopes (I use a
15cm altazimuth reflector).  And there's a certain dimwit with a $20,000
Celestron who reports "novae" to me several times per year - his last
one was the planet Mars!  The moral of this story is "learn your sky".

To learn your sky, the all-sky charts in the astronomy magazines will
help you. "Sky & Telescope" and "Astronomy" have one each month; and you
should soon learn where the constellations and brighter stars are.
Tirion's "Bright Star Atlas" or "Norton's Star Atlas" also have good
charts.  When you become experienced with your sky, the "Sky Atlas 2000"
or "Uranometria 2000" are good atlases for finding fainter objects.

You have a big advantage over me; most astronomy books and guides are
written for Northern Hemisphere readers.  Your local public library may
have a few.  Read them on those inevitable cloudy nights.




cheers,
Fraser Farrell

http://vsnet.dove.net.au/~fraserf/   email: fraserf@dove.net.au
traditional: PO Box 332, Christies Beach, SA  5165, Australia

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