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I'll second the suggestion to get a Dobsonian. I'm not any kind of astronomy expert, but they seem to be the cheapest, simplest way to get a large-aperture telescope. Besides aperture, the other thing to look at is focal ratio. Generally, you'll want a low focal ration like f/5 for looking at large, dim objects like nebulas and galaxies, and a high focal ratio like f/9 or so for looking at small, bright things like planets. I'm in sort of a weird telescope situation in that over the years I've collected three garage sale telescopes of various sizes, and they're all right around f/5. I also live in a city, so they're all optimized exactly for looking at the things I can't see unless I travel pretty far out of town where the sky is dark. My two bigger scopes are made by Coulter Optical. Coulter is an interesting company. As I understand it, back during the 80's or so, you just couldn't buy a large aperture telescope for a reasonable price. So, Coulter came along and figured, "why don't we make a telescope where we put most of the manufacturing effort into a high-quality primary mirror, make the rest as cheaply as humanly possible, and sell the result? The result was the Odyssey 1, with a 13" primary mirror. It looks like large home-made waterheater, and is about as portable. Later on they made the Odyssey 8, a smaller version with an 8" primary mirror. The tube is made of cardboard, and the focusser is just a pvc slip fitting. The base is made of painted chipboard. That's the telescope I use the most, and it works great. I wouldn't recommend the odyssey 1 unless you live out in the country somewhere where you can set it up and use it without having to load it into a car and drive somewhere else. |
Many telescopes come with one or two eyepieces, and you may want to get a few more in various focal lengths. Generally, the tradeoff is long focal length: everything is small and bright, short focal length: every thing is small and dim. So, generally you start out with a long focal length to find the thing you're looking for, and switch to short when you find it and want a closer look (assuming it's something small and bright like a planet).
There are also barlow lenses, which are sort of an adapter with lenses that increases the magnification of whatever eyepiece you're using. They're occasionally useful.
Most mid-range telescopes have standardized on 1-1/4" diameter. Cheap/older telescopes sometimes use 0.96" and big telescopes sometimes go with 2". Adapters are available to mount DSLR camera bodies to the telescope without using any lenses at all, which is a great way to go on a Dobsonian because there aren't any lenses at all in the whole optical path to introduce chromatic aberration, only mirrors. (I don't have a DSLR camera, but in the past I've had a bit of fun taking the lenses off of old USB webcams and adhering them to the focusser shaft with poster putty. I was able to get some decent low-resolution footage of an extreme-close-up of the moon that way.)
Another thing that might be useful sometimes is something you can use to cover most of the telescope aperture, for cases where you want maximum image clarity and are willing to sacrifice light-gathering. That can be handy for looking at the moon.
I haven't tried using filters, but those can also be used to bring out contrast in certain things.