Buying That First Telescope--Part One

Entire books have been written on the subject of purchasing a telescope, so obviously I can't give you all the information you would need in a couple of short articles. What I can do is point you in the right direction, give some tips from personal experience, and explain a little of the jargon you will run into in advertisements and catalogues.

First, and most important: DO NOT BUY A TELESCOPE FROM A DEPARTMENT STORE. They'll certainly be affordable, but that old saying "you get what you pay for" is absolutely true for telescopes. It will be of cheap construction with poor optics on a rickety tripod (I know because that's exactly what my first telescope was) and probably cause you so much grief you'll give up on astronomy before you've even gotten started. If your primary concern is getting the least expensive scope possible, I've seen advertisements for 3" refractors from $80 to $90. That's the absolute lower limit for anything of decent quality. Any scope that is cheaper than that is, well, "cheap."

So what is a refractor anyway? There are four main types of scopes. A "refractor" collects light through a lens. These are generally the smallest scopes. You get very fine image quality and these are good for viewing the moon and planets. If you'll be viewing from an area with lots of light pollution, this is the scope you want. Something more powerful will just magnify the wash-out effect of the light pollution.

The second type is a reflector (Newtonian reflector). These collect light via a curved primary mirror which then bounces the light off an angled secondary mirror to an eyepiece at the side of the scope. These are good all-purpose telescopes, good for planets and some deep sky objects. One disadvantage is that the alignment of the lens and mirrors (called the "collimation") progressively deteriorates requiring occasional adjustment. No big deal, just a bit of a nuisance.

The third type is the catadioptric, otherwise known as the Schmidt-Cassegrain. Light enters the lens which bounces off a curved mirror then bounces off a second mirror straight back to the eyepiece. These are generally the most expensive, but probably the ideal choice for someone truly serious about astronomy who also has access to a good dark sky site to view from. How expensive is expensive? Our 10" Schmidt-Cassegrain cost $3000. Don't faint. Some Maksutov-Cassegrain scopes can be had for anywhere from $500 to $900. There are good scopes available for any budget.

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