However, the image will almost certainly be dim and fuzzy-or “empty.” (Magnification beyond 50x per inch is known as “empty” magnification.) Don’t be drawn in by magnifications claiming upwards of 200x per inch these will almost surely disappoint. You can get an eyepiece that will deliver more than 50x per inch. Most backyard telescopes are between 50x and 100x. For example, a telescope with a 3-inch main lens or mirror will have a maximum useful magnification of 3 x 50 = 150x (150 times). The maximum useful magnification for any telescope is 50x (50 times) the aperture in inches. If an object appears to be 50 times larger through the telescope, the magnification is “50x,” or “50 times.” Magnification is expressed as a number indicating how large an object appears in the telescope as compared to how large it appears to the unaided eye. The eyepiece on the right is homemade by the author. The magnification of a telescope can be changed by swapping out the eyepiece. Typically, the eyepiece can be quickly and easily changed out for one of different magnification.įig. It magnifies the image of the object in view. This is a small, barrel-shape device containing one or more lenses. The light gathered is projected through the telescope’s eyepiece. Parabolic mirror used in Reflector telescope (right). Achromatic lens used in a Refractor telescope (left). (Even a small telescope gathers more light than the naked eye/s.) All else being equal, the larger a telescope’s aperture, the more you can see with it.įig. The size of the aperture determines how much light a telescope will gather. The diameter of the main lens or mirror is called the aperture. The larger it is, the more light it will gather and the easier it will be for you to see faint objects. Telescope BasicsĪ main lens or a mirror is the main optical component of a telescope.

If it’s so complicated that you dread using it, then it’s a poor choice for you.īefore you buy, understand how telescopes work and the differences in types. The “best” telescope is the one that you will actually use. Do I enjoy learning how mechanical devices work, or am I more of an “appliance operator” who simply wants to look at things?.Is astronomical observing something that I will do occasionally, or will I want to get out under the stars every chance that I get?.How deeply into astronomical observing do I expect to go?.

Good telescope for astronomy