Jimmy Westlake: Advice for buying your 1st telescope
March 5, 2013
With the news that a couple of spectacular comets could grace our skies this year, you might be thinking about purchasing a telescope to get a better view. Here are some tips for first-time telescope buyers that I hope will prove helpful.
If your primary goal is to get a great view of Comet PanSTARRS in March and Comet ISON in November, then I recommend your first telescope be a good pair of image-stabilized (IS) binoculars. Each of these comets could appear very large in size, with tails that sweep many degrees across the sky. A telescope focuses in on and enlarges a patch of sky about the size of only a pencil eraser held at arm's length. That's not going to give you the great view of something big like a comet. A pair of binoculars will enlarge a patch of sky about the size of your fist at arm's length. This will allow you to see the comet's head and much of its tail at the same time while making it appear closer and brighter.
Using both eyes instead of squinting with one eye through a telescope eyepiece also is a plus for binoculars. The image-stabilizing feature will help remove the natural wobble introduced by holding the binoculars as you gaze skyward. If the binoculars can be mounted on a camera tripod, no other image stabilization is needed. When the comets are gone, you'll have a great pair of binoculars for viewing wildlife, concerts or sporting events. You can purchase a nice pair of image-stabilized binoculars for less than $500. My Canon 10×30 IS binoculars are always nearby when I am outside observing.
If you still want something that will pull in objects much closer than binoculars can — something that will show you the craters on the moon, the rings of Saturn and the wispy gas clouds of the Orion Nebula — then you'll need a telescope. Backyard telescopes come in a wide range of prices, from less than $100 to more than $10,000, and all telescope companies do not have your best interest and satisfaction at heart. Here are some key points to keep in mind:
1) Don't be misled by claims of 400 or 500 magnifying power on the telescope box. Magnification is the least important feature of a telescope, but marketers know that claiming high magnification increases sales. No small telescope can give a good, clear image at 500X. Instead, you want to put your money into the largest diameter lens or mirror that you can afford. For example, a 4-inch diameter telescope will show the rings around Saturn even at low magnifications of 50X. The larger the diameter of the lens or mirror, the clearer the image will be. I prefer a reflecting telescope, which uses a mirror, to the traditional refracting telescope, which uses a lens. You will get more telescope diameter for your dollar with a mirror rather than with a lens.
2) Look for a telescope that has a rock-solid mount. If it came on a wobbly mount, even the Hubble Space Telescope would be very frustrating to use and would probably be left to gather dust in the closet. Two good mounting styles to look for are an equatorial mount or a Dobsonian mount. Avoid wobbly-legged wooden tripods at all costs.
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3) You can get a "smart" telescope with GO-TO technology that will automatically aim your telescope to any object in the sky that you select on the keypad. This feature will add cost to your telescope but can be most helpful for folks just starting to learn their way around the sky. I used to be a "purist" and only used telescopes that I aimed manually, but the GO-TO technology has become much more user friendly and has dropped in price considerably. My Celestron Nexstar GO-TO telescope is now one of my favorites, especially at star parties. Welcome to the 21st century!
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. Check out Jimmy's astrophotography website at http://www.jwestlake.com.