To look at the sky not just with the naked eye, but through a real telescope, many have a desire. But not everyone gets to the point of buying expensive equipment. To buy a telescope and not be disappointed in the night sky, without spending extra money, you need to figure out what telescopes are and how they differ.
When choosing a telescope, pay attention to the telescope type (refractor, reflector, catadioptric), mount (alt-azimuth, equatorial, auto-aiming (computerized), Dobson), lens diameter and focal length. And now about all this in simple and understandable words.
Refractors (lens) and reflectors (mirror) do not differ much in price, but they have a number of differences. It is convenient to observe both terrestrial and space objects in the refractor, and in the reflector the image is turned upside down, so it will not be comfortable to look at terrestrial objects. Also reflectors are weaker than reflectors, so they need a larger diameter. Another disadvantage of reflectors is that they do not tolerate constant movements poorly, and therefore they need to be periodically adjusted (set up the mirror) and cleaned. But reflectors also have dignity - unlike a refractor, they do not have chromatic aberrations (which we see as colored halos).
Catadioptric (lens-mirror) telescopes have the largest focal length at the smallest size, that is, they are compact. In them, you can observe the Moon, planets, constellations, as well as nebulae and galaxies with the same comfort. But his price will already be much higher than reflectors and refractors.
Now about the mounts. Alt-azimuth is the simplest, does not require any special skills, is lightweight, inexpensive and very mobile. But it has significant drawbacks: on such a mount, you can only observe objects at the zenith (you cannot track moving objects, only re-adjust and expose) and it is not adapted for astrophotography.
The equatorial mount is more convenient: after aiming at an object, you can guide it along the trajectory with just one handle, and it is also easier to find faint objects on it. And due to the presence of a counterweight, you can connect a digital camera and take pictures of space. But such a mount weighs more and costs more.
Computerized (electronic, auto guidance) - easy to use (only the initial telescope alignment is required), has a base from which you can select objects, has a remote control and the ability to update the database data. To work with a telescope on such a mount, no knowledge of the starry sky is required, since it will find and aim at the object that it has in its database.
Dobson is a floor mount designed for observing objects outside our solar system (galaxies, nebulae). She is stable and massive. But you will not be able to view close space with the help of such a mount.
There are two more things to consider when choosing a telescope.
The maximum usable magnification of a telescope is calculated as the diameter of the lens multiplied by two. But it should also be taken into account that the larger the lens diameter, the brighter and clearer the picture will be. The focal length affects the magnification and viewing comfort. The longer the focal length, the more convenient it will be to observe, since decreasing the focus of the eyepiece will noticeably reduce the field of view and comfort.
