What are the Main Types of Astronomical Telescopes?
Astronomical telescopes mainly sort into refractors, newtonian reflectors, and catadioptric Schmidt-Cassegrains which are a mix of both. Refractors are tubes with a lens at their aperture. The lens is forwarding the light to the other end of the tube where an eyepiece is used to further magnify the object. Newtonian reflectors are an open tube at the bottom of which a reflecting mirror. The mirror is sending the image towards the eyepiece through a secondary mirror. The eyepiece location is at the top of the tube, at a right-angle of the instrument. In catatadioptric Schmidt-Cassegrains telescopes -Schmidt-Cassegrains telescopes (SCTs)- light is reaching a primary reflecting mirror through a corrective lens located at the entry of the instrument. The light is reflected from the primary mirror towards a secondary which sends the image further, through a hole in the primary, to the eyepiece. Dobsonians are newtonian reflectors.