If you are new to astronomy your first concern is probably how to buy a telescope. I suggest you start by researching the many different types of telescopes available. Although, you will probably want to start out with one of two basic designs, refractor or reflector, always learn as much as you can about what you want to buy so you can be sure to get the best equipment for your money.
A refractor telescope has only two lenses, one at the far end and one in the eyepiece. The one at the far end is the larger of the two and is called the object glass. While the eyepiece is just that, the one you look through. The object glass focuses the light it collects as a sharp image then the image is magnified and you can see it through the eyepiece. Focus the image by sliding the eyepiece in and out of the telescope.
Advantages of a refractor telescope are higher resistance to becoming misaligned after the initial alignment is complete because the glass surfaces are sealed inside the tube of the telescope. This also means they rarely need to be cleaned and because they are sealed in the telescope tube providing the user with sharper, steadier images.
Disadvantages include many flaws, or aberrations. of the lenses. Meaning subtle distortions like an astigmatism where you will see the image overlapping itself or color changes. Refractor telescope lenses also need to be supported around the edges and so the size of the refractor is limited.
The next type of telescope you will come across when learning how to buy a telescope is a Reflector telescope. Reflector telescopes are different in the way they collect the light coming into the telescope. Light is collected at the bottom by a concave mirror called the Primary. There are many types of reflecting telescopes and the type is determined by how the light is focused once the Primary has collected it.
Sir Isaac Newton developed one of the first designs of a reflecting telescope where the Primary focuses the light onto a secondary mirror placed flat farther up the tube and then into the eyepiece on the side of the telescope.
Advantages of a reflector telescope are the mirrors, they don’t cause color aberrations like a refractor can and are easier to make without defects because mirrors are one-sided. Larger telescopes can be built because of the use of mirrors as mirrors only need support from the back.
Disadvantages include needing frequent realignment and the mirrors will need to be cleaned every now and then.
As I said, these are the two basic types of telescopes most used by brand new star gazers but there are many other types available. Depending on your what your price range is you may find something a little more expensive may give you a more enjoyable experience.
Keep these things in mind when figuring out how to buy a telescope for your new found hobby of astronomy.