Rm. H5: Telescope Basics. (under construction)

Considerations in Buying a Telescope for Beginners

Telescopes are not that complicated to understand. All telescopes have a main light gathering element or aperture. This light gathering element can be a lens, mirror or combination of both. This aperture gathers the light and sends it to the eyepiece. The eyepiece is a combination of lenses that magnify the image gathered by the main aperture. The telescope relies upon a VERY stable mounting platform so that it can be moved to point in various directions. Because a telescope sees only a very small part of the scene, it needs a very accurate method of being aimed. This is usally done with a finder scope. A finder scope is a small telescope that sees a larger area of the scene and usually has cross hairs in the center to aim with. There are varoius filters available for use with a telescope that can help with specific situations such as dealing with light pollution. For more information see the telescope section.
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The price of a scope depends upon many factors, but the most important factors are the optics and the mounting. The main optic categories for a telescopes are: These telescopes each have their strengths and weaknesses (see telescope section), but are all suitable for viewing the heavens.
The main reason for the differences in cost is the difficulty in making the optics, with lens the most expensive per inch to make and mirrors the least expensive.
Another major price consideration is the mount. You can get a Dobsonian mount. It is cheapest to make and is very stable but it is very difficult to get it to do tracking. For a little more money there is the Alt / Azimuth on a tripod (make sure it is stable - no tracking). or a German Equatorial mount with tripod (generally $100+ added to price of scope -tracking), and a Fork mount with tripod (gets very expensive for the bigger telescopes - tracks).

See price comparison chart

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Size of Main Lens or Mirror
The main difference in the price of the telescopes is caused by the size if the main lens or mirror and you may question what do you get for that price. Contrary to popular belief, high magnigication of the image is not the most important part of a telescope. The light gathering power of a scope is. Most opbects are faint and need to have the light comming from it magnified so the image becomes bright enough to see. The larger the amount of light entering the scope the fainter the object can be detected. See the following examples for an idea different sizes can make. The small scopes are still good for seeing brighter objects like planets, Moon, and brighter deep space stuff.

Example views through size scopes at the same magnification.

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So far it looks like the only consideration would be how big of a telescope can I afford. There is another important consideration before choosing - how easy is it to move and set up. If you live in or near the light polluted city you will want to take your scope to the country where it is dark. Light pollution can render the views of a 10 inch scope to close that of a 2 inch scope. So many telescope owners want to move their scope from place to place. If the scope is to big and heavy it won't get moved much and will often find some out of the way corner of the garage/attic/basement to sit and never be used. A 2 inch scope that is used is far more enjoyable than a large scope that just sits some where just because it is to difficult to move.

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Ease of Setup
Another consideration is how easy is it to setup the telescope. A telescope that has a German Equatorial Mount is a lot harder to setup than a telescope that is on a Dobsonian mount. It takes about thirty seconds to have a Dobsonian ready for viewing, about 2 minuets for a telescope on a Alt / Azimuth mount, 1 to 10 minuets for a small (3 - 5 inch) telescope on a fork mount depending if you set it up to track or not, whereas a telescope on a German Equatorial mounted scope takes longer depending upon your skill at setting it up and aligning it.There are good reasons to get a telescope with a German Equatorial or Fork Mount, this is because they can track objects for ease of viewing and photography whereas a Alt / Azimuth or Dobsonian basically can not track at all . Another consideration is a telescope with a fork mount. They are far easier to set up than a German Equatorial Mount and work very well tracking, But get quite heavy when you get to the larger scopes.

Dobsonian Mount - Cheap, fast and easy to set up, stable, bulky, no tracking.
Alt / Azimuth Mount - inexpensive, easy to set up, CAUTION! may be instable if too cheap, lightweight, no tracking
German Equatorial Mount - Average added cost $150 (avoid cheap ones), tracking, motor drive option. requires alignment during setup.
Fork Mount - Most expensive for larger telescopes, does not require alignment for quick viewing, Tracks, can come with motor drive.

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Most telescopes come with some accessories included when you buy them. Minimally they will come with one eyepiece.
You will need a STURDY tripod with all telescopes except a Dobsonian.
You will need a finder scope with mount or a Telrad type finder.
You will probably want another eyepiece for higher power.
You will need a map of the night skies for your date and roughly your latitude. this can be a Plainisphere, a chart out of one of the astronomy magazines or print out Astronomy sky chart program.
You will need charts of deep space objects either from a book or an Astronomy sky chart program.

Note: Avoid department store/sporting good 2" (60mm) telescopes!
They are generaly fair to poor in quality and highly over priced.

Known decent telescopes brands that I am familiar with:
Coulter Optics

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