equipment
Overview
Telescopes are the instruments that most people will immediately think of when you mention astronomy. Although there are many other instruments available to the amateur astronomer, including binoculars and the naked eye, the most widely recognized astronomical instrument is the telescope.
Telescopes are classified in one of three general categories that describe the design of the telescope. The refracting telescope, which uses lenses to focus the image, the reflecting telescope, which uses mirrors to focus the image, and the cadioptric telescope, which uses a combination of lenses and mirrors to focus the image.
Refracting telescopes are usually found in the 6" aperture or smaller range because of the expense and difficulty of creating large lenses. Refracting telescopes generally provide high contrast images and are popular as planetary scopes where their high contrast images are preferred and their smaller apertures are not a liability.
Reflecting telescopes, of which the Newtonian design is the most popular, are found in the 3" to 36" aperture size. While reflecting telescopes do not provide the same high contrast images that reflecting telescopes provide, the less expensive mirror system in a reflecting telescope allows the telescope maker to create larger aperture reflecting telescopes for the same cost as a smaller refracting telescope. Some amateur astronomers manufacture their own mirrors for their telescopes. The larger apertures allow the user to view much fainter objects, albeit with less contrast than their counterparts. The reduced contrast generally has no effect on the feeble light from a galaxy millions of light years from Earth.
Cadioptric telescopes, of which the Schmidt-Cassegrain and Maksutov are the most common, are found in the 4" to 16" aperture range. Cadioptric telescopes are popular because their inherent design creates telescopes that are smaller in physical size and weight. A 10" aperture cadioptric telescope can be one-half to one-third the size of a comparable 10" Newtonian telescope.
The telescope that is right for you is the one that you will setup on every clear night of the year. The telescope that sits in the closet because it is too big, too heavy, or too complicated to use provides no enjoyment at all. The following is a list of the telescopes that I have owned over the years.
