Newbie asks about xmas scope...

To Simon

Go ahead and join the Newtonian astrologers here,their really profound
celestial concepts are helping humanity understand things like climate
imbalance and how the Earth tilts towards and away from the Sun to
generate the seasons -

http://www.diduknow.info/sun/images/high_low_sun.gif

The guy who was overjoyed with the "crescent of Venus" is unlikely to
appreceate the relationship between Venus and the Sun in terms of
heliocentric astronomy,the size of our parent star or indeed that
Venus is roughly the same size as the Earth -

http://home.cogeco.ca/~astrosarnia/P...Web%20view.jpg

You want your celestial peep show with your
sunrise/sunset,constellations,crescent of Venus,variable axial tilt and
all those things which are astrological fun but the real astronomical
insights give a satisfaction that is impossible to describe.The real
treasures of astronomy cost nothing such as recognising how the
Ptolemaics seen epicycles while Copernican heliocentrists seen the
annual orbital motion of the Earth.Then and only then are you doing
astronomy -

http://antwrp.gsfc.nasa.gov/apod/ima...2000_tezel.gif

Hi Simon,

On 30 Dec 2005 10:59:02 -0800, "Simon James"
wrote:

My wife purchased a telescope for me for xmas from a site called
"bestoptics". It's a Bushnell Northstar reflector, 76mm aperture,
900mm length with goto.

The scope came with two eye pieces and a barlow lens that looks like it
fell out of a cheap cracker. I've ordered a set of six eye pieces from
South West optics and some filters, seemed a bargain at just £99.
Hope they're better than the rubbish the scope came with! (SR4mm and
SR20mm).

They should be much better. As you know, the maximum magnification
that you can expect to be able to use is twice the aperture or the
'scope in mm (same as 50x the aperture in inches): 76 x 2 = 152. As
your new telescope is 700mm focal length this means an eyepiece of
700/152 = 4.6mm. Now it is likely that you will only be able to use
that magnification on very steady nights so I would think that the 6,
9 or 12mm eyepieces will be in the right range, giving magnifications
of 117, 78 or 58. When observing, use the lower magnifications first
and work up. Do ensure that the telescope is cool before using it,
leave it for a least half an hour or more to reach the same
temperature as the chilly outside.

My one fear now (having not yet had a good try of the scope) is that
the 76mm mirror will not be enough to see saturn, for example, at any
decent magnification.

You will be able to see Saturn when the air is clear and steady enough
and the telescope in well collimated, but don't attempt any
collimation yet, you need to use the 'scope for a while to get used to
how the image is affected by the varying atmosphere and the different
magnifications that suit it.

Needless to say I fell for the 525x mag as
described on the site the scope was purchased from, that was before I
understood about the 50x per inch guidelines, etc.

Yes, it's very deceptive, that sort of advertising and very common
too.

My question is,
does anybody know of a site where I can view images that were taken
using a 3" reflector scope such as mine so as I can compare what I see
with the art of the possible and decide whether or not to upgrade
sooner rather than later!

There is the, rather good, 60mm refracter site at:

http://astrosurf.com/l60/en/index_en.html

Regards

- Mike

"Simon James" wrote in message
oups.com...
oriel, you don't half talk a lot of garbage.

Very perceptive, and well said.

Thanks for the replies, and a special thanks to Mike for his reply;
very useful.

The sky cleared last night and although my new eye pieces are yet to
arrive, I did indeed catch Saturn for the first time with the 20mm
cheapo eyepiece. Couldn't get it focussed with the 4mm, but not to
worry. It appeared a lot smaller than I was expecting!

Si

Simon James wrote:
The sky cleared last night and although my new eye pieces are yet to
arrive, I did indeed catch Saturn for the first time with the 20mm
cheapo eyepiece. Couldn't get it focussed with the 4mm, but not to
worry. It appeared a lot smaller than I was expecting!

As has been mentioned, I dont think anything less than 9mm will be much
use, apart from very bright objects, such as Venus and Mars at the
moment, as well as close-ups of the Moon.
I've got a similar magnifictaion set-up as you, a Skywatcher 900mmx70mm
refractor.For light use it is fine, I generally use a 25mm lens, which I
find is best for nearly everything, earlier this year Saturn and a
couple of its moons were clearly visible with the 25mm, I then tried it
with the 10mm, but it was only just usable - the image was then a lot
darker, and because the supplied tripod/mount is not brilliant, any
slight nudges on the scope make it wobble so much as to make it
virtually unusable.
I think we have been seduced by the images from the Hubble telescope,
and think that spending a few hundred pounds will make us see such
things, but the reality is rather different.
I find, even after a year, that on clear nights, when it isnt too cold,
it is still amazing to see the amount of stars out there, which are just
not visible to the naked eye.
Alan.
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In message
(Jim) wrote:

Mark Dunn wrote:

Eh?

Gerald is our resident troll. He bangs on and on and on like a stuck
record about 'heliocentric this' and 'equation of time that'.

It's best to just ignore and/or killfile him.

You forgot "And do *not* repost his crap in its entirity unless you want
to join him in the kill file" I think...

Anthony