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What telescope should I buy?

Reflectors, Refractors and Binocs - oh my!

For those who are less of the "do it yourselfer" type, and want to be able to plop down some cash and get on with observing already, I figured it might be helpful to write a bit about how to decide what is a good "first" telescope. For those where money is no object - well, this section isn't for you! But if you - or a son or daughter or relative or friend - is considering purchasing a telescope for use in the backyard to 'see a few things' - then read on.

First: Consider GOOD binoculars

An often overlooked - but highly useful, and good - optical instrument for any amateur astronomer is a set of binoculars. Most first time astronomers scoff at binoculars, thinking, "I need a telescope to do astronomy!" Well, no - all you really need is your eyes. Lots of astronomical observing can be done without any optical aid whatsoever: Lunar eclipses, meteor showers, brighter variable star observations - all are best done without ANY optics!

But some increase in light gathering capacity beyond our eyes and a bit of magnification does help. And there a many reasons why binoculars are a good first choice:

1. They keep the same orientation as your eyes - up is up, left is left, etc. (astronomical telescopes reverse some, or all orientations)
2. Most provide a good, wide field of view, which is important when finding many objects such as the Pleiades or other large area deep-sky objects
3. They're easy to aim at objects
4. They also can be used in the daytime for birding, ship watching, etc.
5. If interest in astronomy wanes, they have other uses
6. Decent ones can be had for under $100

What to look for in binoculars

First, it helps to understand what the numbers associated with binoculars mean, like 8x42 and 7x50 or 15x70. The first number is the magnification that the binoculars provide. The higher this number, the larger the object will look when you view it. But correspondingly, as magnification increases, so does the difficulty in holding the binoculars steady while viewing. A 15x binocular will appear to "jiggle" twice as much as a 7x binocular, given the same hand movement. Anything above 10x magnification is difficult to hold still hand-held, and requires a tripod or some other steadying mount.

The second number is the size of the objective lenses - those are the big lenses through which light enters. The larger these are, the more light gathering capacity they will have. As these lenses get above 50mm (about 2 inches), they become much, much more expensive, in general. 40 to 50 mm objectives are fine, though 50mm is typical for astronomical use. NOTE: The "straight through" type binoculars - usually very small ones, like 8x22 or 8x30 - use a different kind of prism, and also do not collect much light for night star gazing. Although small and compact, they are generally not as useful for astronomy, but if that's what you have or are able to get, they will work. But I don't recommend them.

DO look for binoculars that have anti-reflective coatings. High quality coatings should appear greenish, purplish or bluish on the lenses. DO NOT get the "ruby coated" ones - they are cheap binoculars, and that coating doesn't do any good anyway! DO try to get binoculars that have a tripod mount adapter - if you decide to put them on a photographic tripod to steady them, it's nice to have that option later. DO NOT get the "focus free" types; the binoculars should have some method for focusing for different individuals' viewing needs. DO NOT get "zoom" binoculars!!

Most amateur astronomers have a set of 8x42, 7x50 or 10x50 binoculars. 7x50 is a good first choice, as it gives a wide field of view, and there are many of this magnification and lens size available. Some people sell older binoculars on Craiglist or Ebay - look for the "do's" and "don'ts" above to know what to look for, and what to steer clear from. For some good new binoculars, here are a few that I think are good options:

• Orion 7x50 Scenix binoculars - about $100*
• Orion 10x50 Worldview waterproof binoculars - about $80*
• Orion 8x40 Worldview waterproof binoculars - about $70*
• Nikon Action 7x50 binoculars - about $70*
• Bushnell 7x50 Falcon binoculars - about $35* (these are about the least expensive ones I'd recommend, and they are not going to be as good as the ones above, but they will make a good set of "starter" binoculars. You'll probably want to replace them in a year or two, but the learning experience will be very helpful.)

Although other binoculars can be bought for less, a good set of binoculars also is well-collimated (meaning both sides have images that match up, so no eye-strain for you when viewing), has decent anti-reflective coatings (increasing light transmission for more faint objects to reach your eye), and in general will be better made and last much longer. It's worth spending a little extra, even if you have to wait to get them.

But I really, really, REALLY want a telescope!

Okay, okay... click over to the next page and we'll talk telescopes.

One last thing: Please be sure to turn off your outdoor lights, or if you must have an outdoor light on, be certain it is a full cut-off fixture, and the minimum wattage required. No sense in lighting the underside of planes at night - it just ruins the night sky for everyone else! Besides, doing so really will save you money on your electric bills. For more information about light pollution, please visit the International Dark Sky Association.