Telescope Buying Tips
When buying a telescope, you'll find amateurs, experts and those who once took an astronomy class in college happy to share a bewildering amount of information. Before getting bogged down with opinions, think carefully about what you plan on using the telescope for. Much like picking out a bike, you can't just ask for a pink, sparkly one; you must take into account what you plan on using it for.
Many serious hobbyists will tell you that the first thing you do is walk right by the department store telescopes. They even have a nickname -- "Christmas junk" -- in astronomical circles, due to their reputation for shoddiness. Many of them offer extremely high magnification as an enticement, but you can easily increase magnification by changing the eyepiece, so don't be tempted by claims of 800 times magnification for a hundred-dollar scope.
Instead, do look online for reputable dealers recommended by Astronomy Magazine or Sky and Telescope magazine. Beyond that, ring up your local astronomy club and attend a session. The members will have a variety of different scopes and will be happy to let you have a look (along with some good advice, no doubt).
In terms of looking for magnification, remember that higher isn't better. Too high and you're blowing up what you're seeing to the point of losing clarity. To make sure you're not being had, you can calculate the maximum useful magnification of a telescope by multiplying the size of the lens or mirror by 50 (that is, a telescope with a lens measuring 8 inches, or 20 centimeters, across should have a maximum magnification of 400 to work optimally). Greg Scheiderer, editor of SeattleAstronomy.com, recommends buying several different eyepieces with different magnifications anyway, to experiment with when viewing.
In terms of type, a refractor or reflector telescope -- or one that uses dual technology, called a compound or catadioptric telescope -- are all fine. Although refractors are generally more expensive, reflectors have equally good quality. If you're buying for a kid with a nascent interest, keep in mind that a scope with a 4-inch (10-centimeter) lens might be just fine to start out with; if you've got a more serious hobbyist on your hands, best to stick with something between 6 and 10 inches (15 and 25 centimeters). And remember, the bigger the telescope the more difficulty you might have working with it.
"The best telescope is the one you'll use," as Greg Scheiderer points out. With mounts, photography options and even smartphone apps adding to the stargazing experience, let's zoom in on the next page to pinpoint what kind of telescope -- and accessories -- might be right for you.