Buying a TelescopeAssuming you have a fixed budget, you should buy the highest-quality optics and the largest-diameter telescope you can afford. Of the two things that limit what you see, optical quality is under your control. You can't make the atmosphere less turbulent, but you should buy good optics. If you buy a telescope from a toy store and it has plastic lenses, you shouldn't expect to see very much. Also, you want to maximize the light-gathering power of your telescope, so you want to purchase the largest-diameter telescope you can afford. Given a fixed budget, that means you should buy a reflecting telescope (which includes Schmidt-Cassegrains) rather than a refracting telescope. Not only will you get more diameter (aperture) per dollar, but your telescope will not suffer from chromatic aberration. You can safely ignore magnification. Department stores and camera stores may advertise telescopes by quoting their magnification, but it is not an important number. What you can see is fixed by light-gathering power, optical quality, Earth's atmosphere, and local light pollution. Besides, you can change the magnification by changing eyepieces. Other things being equal, you should choose a telescope with a solid mounting that will hold the telescope steady and allow you to point at objects easily. A sidereal drive would be very useful even on small telescopes, and computer-controlled pointing systems are available for a price on many small telescopes. A good telescope on a poor mounting is almost useless. You might be buying a telescope to put in your backyard, but you must think about the same issues astronomers consider when they design giant telescopes to go on mountaintops. updated: |