From a no-frills beginner's telescope to an advanced computerized model, a superb selection of tempting equipment awaits the telescope shopper.
For the first-time buyer, the extra-ordinary variety of telescopes available can be overwhelming. There are three main optical designs. Reflecting telescopes use a mirror to gather light; refracting telescopes use a lens. A third type of telescope, the catadioptric, uses a combination of a mirror and a lens. Schmidt-Cassegrains and
Maksutovs are examples of catadioptric telescopes.
Each of these three types has its selling points. All of them can show you details on the Moon as tiny as a mile across, the stunning rings of Saturn, the changing clouds of Jupiter, and the brightest galaxies, nebulas, and star clusters of deep space.
When shopping for a new telescope, the choice of optical design is less critical. Most importantly, avoid any telescope sold by how much it can magnify. Low- quality telescopes are often promoted by claims such as "450 power" or "high-power professional model." Many of the 2.4 inch (60 mm) refractors and 4.5 inch (110 mm) reflectors commonly seen in camera shops and department stores fall into this category. They feature wobbly mounts, eyepieces and finderscopes with poor optics, and plastic fittings. The views through these "toy" telescopes are disappointing, to say the least. However, there is nothing inherently wrong with smaller telescopes. A good 2.4 inch (60 mm) refractor with the features in our checklist can make a fine starter scope.
Most telescopes are sold with at least one or two eye-pieces. Try to find a telescope with quality eyepieces—such as Kellner, Orthoscopic, Modified Achromat, and Plossl types—giving no more than 75 to 100 power. Additional eyepieces can be purchased separately, but if the telescope provides only high-power (150x to 300x) eyepieces, it is probably of poor quality and should be avoided. Most basic telescopes accept only 0.965 inch (24.5 mm) diameter eyepieces, but if you are prepared to spend a bit more, look for a telescope that takes the better grade of 1.25 inch (31.8 mm) diameter eyepieces.