Re: [OT] Telescopes...

[David Paterson <david.paterson@xxxxxxxxxxxxxx>]

I knew I couldn't be the only astronomer on the list :)

Just to add a few comments to Mal's...

>As a rough guide, I bought a cheapish 6" reflector (Skywatcher
Explorer 15=
0)
>for =A3350 from Venturescope (www.telescopesales.com.uk).  This is
probabl=
y a
>reasonable first scope, but if you get the bug you'll quickly want a
large=
r
>one.

Yup, a 6" is a good starting size, as it's easily portable for getting
it in and out of the house, or in the car, and it's easy to learn how to
set it up and operate it.  And if you don't really get into astronomy as
a hobby, it's not hard to sell either.

>It came with a motorised EQ3 equatorial mount (meaning it can keep
>pointing at the same star as the earth rotates).  A motorized mount is
vit=
al
>IMO - without it the object you're looking at will quickly drift out of
>view.

Motor drives are handy, but not essential.  I didn't get them at first,
and you soon learn how to keep turning the RA knob at just the right
speed to track things :)

Without drives you can save about =A3100 off the price.

Of course if you've got a biiiig budget then you can get a GOTO system,
which has a computerised database of objects, and which will point you
at just about anything interesting in the sky.  This saves a lot of time
finding things, and although some people frown on them they do help
people get into observing very quickly.  (I'm thinking of getting one
for my next scope, even though I've spent years learning the sky.)

>With this size telescope you can see Jupiter and it's four largest
moons
>(Jupiter appears as a small disk, but you can make out some banding -
the
>moons are just bright points).  You can also get a good view of Saturn
- t=
he
>rings are visible as a white circle around the planet (or they were
last
>winter - I don't know how quickly that changes!).

The rings are more edge-on this winter, but will still be a nice sight.
Jupiter's always worth looking at, with the moons changing all the time,
and the great red spot crossing every so often.

>The moon of course comes out bright an clear - a bit too bright really.
 I=
'm
>going to buy a moon filter soon.

The Moon is an amazing thing to study (some people hardly look at
anything else).  The detail visible even in a small telescope is
incredible, and the changing light and shadow through the lunar phases
keeps bringing new things into view.

>I haven't really looked for nebulae etc - I only got the scope last
>Christmas and there's been a lack of clear nights this year.  I imagine
th=
at
>they will mostly show up as faint fuzzy patches.  I've just ordered an
>adapter for my digital camera, so I hope to get some good picks with a
lon=
g
>exposure.

Visually galaxies and nebulae are not stunning, especially in a 6",
but
are worth the effort of looking for them.  Using averted vision (looking
out of the side of the eye) will show them more clearly, but it takes a
bit of practice to learn the technique.

One thing that often disappoints people is not seeing much detail in
these kinds of objects.  Unfortunately Hubble has raised expectations
and they expect brilliant coloured nebulae or detailed spiral galaxies,
but even with a huge telescope, like a 24" monster, you just don't see
a
lot of detail with the eye.

To really get that sort of detail you need to take long exposure photos
or images, and a digital camera should get some nice shots (or a
modified webcam as I use).

>If you're willing to spend a bit more, I'd recommend buying an 8"
or 10"
>reflector - it will be worth it.

But don't go mad! :)  I've heard so often about people going out and
buying huge telescopes for their first instrument, and then finding them
unwieldy, hard to move into position, difficult to use etc. and losing
interest in the whole thing.

>The highest practical power
>(magnification) is 2 x the aperture in mm, so a 6" reflector has a
limit o=
f
>150mm x 2  =3D 300.  If you use eyepieces that give a higher power, it
wil=
l be
>impossible to focus the image.

Even 300x is pushing it for a 6" as you need very good conditions to
achieve it without a lot of shimmer or wobble.  But most things you'd
want to look at don't need that kind of magnification anyway.  If you
think that the average binoculars are maybe 7 times magnification, a
telescope giving you 200 or 250 times is a big jump :)

Also, as Mal said, avoid the Argos etc. type scopes, with their "700
times magnification" sort of claims.  The optics are pretty poor
quality.  As with most things, you get what you pay for, and anything
under =A3200 is probably going to be a disappointment.

A couple of final things.  Beware of solar filters - the only safe kind
are the ones that go over the outer end of the telescope.  Eyepiece
filters can get hot and crack.  Or use a projection system for solar
observing, which is much safer.

The other thing to do is contact your local astronomy club.  There's
bound to be one near you, and they'll give you more advice on buying a
telescope.  They'll also have meetings and observing sessions where you
can learn good observing techniques and how to get the best out of your
scope.

They'll also talk to you non-stop about astronomy - pretty much as I've
done above :))

David P.

PS - if you can't find details of your nearest club, drop me a line and
I'll look it up for you.

--=20
David_Paterson =3D david.paterson@xxxxxxx =A6 david.paterson@vissci.=
com;

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