As simple as telescopes look from the outside, once you start looking into purchasing one, they become very quickly very complicated. Understanding specifications like aperture, focal length, f/ratio, and others are vital in choosing one. But let me start by laying out the different types of telescope designs and their advantages and disadvantages.
But let me first say that many advice to start off with binoculars. They are great to look at the Moon, some of the planets, or huge and bright deep space objects like ‘The Pleiades’.
There are 2 major types of telescopes:
- Reflectors: telescopes that use reflective mirrors as objectives to generate images
- Refractors: telescopes that use refracting lenses as objectives to generate images
These are the 2 types of telescopes I have evaluated in my search for my first telescope. There are others that use a combination of lenses and mirrors to generate images. These are called ‘Catadioptric’ telescopes. The most popular among them are:
PBS Crash Course astronomy made a great video on telescopes, their history, and their purposes.