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How to Buy (and Not Buy) a Telescope

A revised and expanded version of this article appears on The Old Farmer's Almanac web site in two parts.

Astronomy is a hobby that can hold your attention for a lifetime, so it's worth starting out right. That doesn't mean you must spend a fortune. But whatever your price range, you want to get the most for your money.

The vast majority of inexpensive telescopes are purchased during the holiday season and given as gifts, mainly to children. Inexperienced buyers make the same unfortunate mistakes year after year. It is far too easy to spend your hard earned dollars on poor quality instruments, and the awful performance of these telescopes often discourages the recipients from pursuing their interest in astronomy. This guide, and the links that follow, will help you spend your telescope dollars wisely.

Planisphere

A Planisphere. Several are available from Sky & Telescope.

The Rules
There are three important rules for buying a telescope.
1. Learn the sky before you buy.
2. Know what to look for in a telescope.
3. Purchase from a knowledgeable vendor.
Let's look at each of these.

Rule 1: Learn the sky before you buy.
Buying a telescope before you know your way around the sky is like buying a car before you know your way around town. Unless you know where you are going, a telescope will not help you get there.

Except for the moon, which is easy to find, the locations of most other night sky objects aren't particularly obvious. In the excitement of using your new telescope, simply pointing it toward a random part of the sky can be interesting. However, frustration sets in quickly when you realize that you have no idea how to find the really interesting sights that await you in the night sky.

At the very least, you need to be able to identify the bright stars and major constellations with your naked eyes. A simple device called a planisphere is a great tool to begin learning your way around. Planispheres cost between $5 and $20.

Along with a planisphere, you'll want a good book or two to help you understand what you're seeing. Click here for some recommendations.

Binocular
A good-quality binocular, the UltraView. Available from Orion Telescopes and Binoculars.
An excellent alternative to telescope ownership is a pair of binoculars. Many of us already have binoculars tucked away in a closet, and these are a fine way to increase your enjoyment of the night sky. With binoculars, a whole new level of detail becomes visible. There are entire books devoted to binocular astronomy.

Binoculars have the important advantage of presenting you with a normally oriented view of the sky. In contrast, astronomical telescopes usually present an image that is either upside down, mirror reversed, or both. Binoculars are extremely convenient, too; just grab them and go! Check out Binoculars: Halfway to a Telescope.

I know its hard to resist the immediate gratification of owning a telescope – it's especially difficult for kids – but you'll be much happier in the long run if you learn the sky before you buy. Once you know the constellations and the stars with your naked eyes or binoculars, and you're yearning for more, that's the time to step up to a telescope.

Rule 2: Know what to look for in a telescope.
What's the most important specification of a telescope? Many people mistakenly believe that magnification or "power" is most important. That is not correct. In fact, "power" is virtually irrelevant in choosing a telescope!

Makers of poor quality telescopes take advantage of this common misunderstanding by claiming their telescopes provide absurdly high powers, such as "525x" or "675x." It sounds good, but this is a sure sign of a poor quality telescope; AVOID IT!

»» NEVER buy a telescope whose main selling point is its "power!"

Actually, the main purpose of a telescope is not to magnify, but to gather light. The more light you can gather, the more you will see. The light gathering ability of a telescope is determined by the diameter of the scope's main lens or mirror.

Once you have gathered the light, then you can adjust the magnification of a telescope by using different eyepieces, much like changing lenses on a camera. Any telescope can be made to provide a wide range of magnifications, simply by changing eyepieces.

As a practical matter, very few telescopes – even extremely expensive ones – are capable of providing good, clear images at absurdly high power. For general observing, low to moderate power is much more useful than high power. Most observing is done at magnifications of 50x to 150x. Absurd magnifications such as "525x" or "675x" are rarely used except in very expensive telescopes in pristine viewing conditions.

Rule 3: Purchase from a knowledgeable vendor.
Department stores, discount stores, online auctions, and TV shopping networks often sell low quality telescopes at inflated prices. This is where you'll find outlandish claims about the "power" of their cheaply made telescopes, because high power sounds impressive. But now you know (see Rule 2 above) that "power" is not an important factor in selecting a telescope. And "good luck" if you attempt to seek advice or assistance -- the places that sell such telescopes generally know little or nothing about them.

The best place to buy a telescope for star gazing is from a dealer who specializes in astronomy. Not only will you get a better value, but you'll establish a relationship with a vendor who can provide advice, accessories, and service (should it ever be needed). Dealers are generally quite willing to explain things and recommend a scope that is right for you.

Most major cities – and many smaller ones – have at least one good telescope store. It's worth seeking them out.

There are also some excellent mail order houses. Some of their catalogs amount to a mini course in astronomy. Buying from a mail order dealer does not give you the same personal service you get from a store, but their prices are generally a little lower.

This is not to say that you'll never find a good telescope in a discount store or on a TV shopping channel or online auction. Good telescopes are occasionally available from all of them. But you have to know exactly what you're looking for, and even then, the prices are seldom a bargain.

Links
For more in-depth discussion and practical advice on what to buy, here are some web sites that do an excellent job of explaining your choices. Take the time to digest the information so you understand the pros and cons of the various options.

Clear skies,
, Astronomy Boy



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