Newbie questions

 
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dino_bobba_renno
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PostPosted: Wed Apr 30, 2008 10:39 pm    Post subject: Newbie questions Reply with quote

I was looking into getting my first scope and I think I have it narrowed down to either the:
Celestron Astromaster 130 EQ Reflector
or the
Celestron AstroMaster 90 EQ Equatorial Refractor Telescope

I've read a bit about the pro's and cons of the differing telescopes but really between what should I expect as far as image size (of say Saturn), clarity and brightness between these two differing kinds of scopes?

One thing I have to admit to is that I'm a little intimidated by the EQ mount. Laughing Am I getting myself in over my head or is it something that you can learn after a few tries?

I can afford a telescope that's more expensive with a moterized GoTo mount but really I just kind of wanted a scope with good image quality for looking at planets and maybe nebula's with my daughter.

Also, what is the learning curve for scopes like these? If I'm better off simplifying a bit to begin with or is this something I can maybe gradulally catch on to enough to spot planets after a 3 or 4 times out?
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Jne_K
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Joined: 24 Sep 2003
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PostPosted: Thu May 01, 2008 5:46 am    Post subject: Reply with quote

Hi

You can use either for planets or for deep-sky work, effectively, though the larger scope would have a slight edge for deep-sky. Also, you can start observing both planets and deep-sky, right away. No great trick to locate planets. Just check their present position in Astronomy or Sky&Telescope if you are not sure. For deep-sky, get a good star atlas and you're set.

No, an equatorial is not to be feared. Just takes some getting used to and polar alignment, at least for visual work, is not at all difficult.

Either one is a good beginners scope.
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PostPosted: Thu May 01, 2008 8:05 am    Post subject: Reply with quote

Which one would you consider to be the bigger scope? I'm not sure how to compare a reflective scope to a refractive scope in terms of size. Would a 130 mm reflective be some what equal to a 70mm refractive? Or am comparing apples and oranges here?
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Jne_K
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PostPosted: Thu May 01, 2008 8:12 am    Post subject: Reply with quote

Hi

A refractor is slightly more light efficient than a reflector. A reflector uses a secondary mirror in the light path, which leads to some light loss (secondary obstruction), but this is not enough to make up the difference between a 70mm rafrqactor and a 130mm reflector. Not even close enough to make up the difference between a 90mm refractor and a 130mm reflector. The diameter of the lens or mirror is still the biggest single factor in telescope performance, assuming all else equal. The 130 is easily the larger scope anyway you look at it.
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PostPosted: Thu May 01, 2008 8:15 am    Post subject: Reply with quote

Oh ok, thank you very much for your help Very Happy
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Jne_K
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PostPosted: Thu May 01, 2008 8:24 am    Post subject: Reply with quote

You are very welcome.
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