Matching the Telescope to the Site

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An important consideration when picking the best telescope is the observing site. Can observing be done from your home? If so, are the skies dark, or are they heavily light-polluted? Are views restricted by trees, houses and streetlights? How far will the telescope have to be carried?

Avoid fast f/4 and f/5 telescopes of any size if you are plagued by bright skies. They perform optimally under dark rural skies for wide-field sweeps along the MiIky Way. From light-polluted sites, f/6 to f/l 5 systems are best – in general, they have better optical quality than ultrafast telescopes have and yield higher powers with a given set of eyepieces. Both characteristics will provide more pleasing images of the moon and the planets.

If there is little possibility that your telescope will be used at home, then focus your decision on portability and ease of transportation. A 4-to-8-inch Schmidt-Cassegrain or a 3-to-5-inch refractor on a fairly lightweight equatorial mount will probably be used far more than a bulkier instrument.

For dark-sky views, it will likely be necessary to drive far from the city. Some of our colleagues argue that if they have to drive for an hour or more to a dark site, they want equipment that will show the smallest, faintest deep-sky objects possible – a 10 inch or larger telescope. Such rationalization works for some people, but we have found that telescopes requiring more than 10 or 15 minutes to load into a vehicle or to set up suffer a steady decline in use after the first year of ownership. You soon find yourself saying, “I’ll go observing some other time – it looks as if it’s going to cloud up,” or “It’s too windy tonight,” or any number of other excuses, all of them cover-ups for the real reason: it is too much trouble to set up the telescope. Instead of enjoying it, you feel guilty for not using it. And a year or two later, you will probably sell it.

On the other hand, if your backyard is protected from streetlights or yard lights, you almost certainly can do some profitable observing, even if you cannot see the MiIky Way. If it is visible, even a hint of it, then consider doing the majority of your observing from home. Some of the advantages of the pristine skies of the countryside are lost, but the convenience of being in your own yard for routine observing or just for quick peeks is wonderful. Travelling to an observing site with your equipment inevitably becomes a tedious affair which is soon restricted to free weekend nights that look as if they may be perfect – a rare combination.

We may be belabouring our point about portability and convenience. But we feel that instead of choosing among refractor, reflector and catadioptric telescopes and then deciding on additional accessories and electronic gadgetry, you should base your decision on the specific observing situation. The best telescope in the world will not be any good if it sits unused because it is too awkward to set up or is not suited to the local sky conditions. Do not delude yourself by thinking, “Oh, that won’t happen to me. I want the biggest telescope I can possibly get.” That is aperture fever.

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