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Telescope Buyers' FAQ - Part Seven

What is the Best Mount?

Equatorials vs. Altazimuths: the Truth
The various telescope mounting systems available for use by amateur astronomers have been discussed at length on sci.astro.amateur. There has been a great deal of debate, a little ill-informed opinion, and some real misconceptions concerning each of the basic mounting schemes, so perhaps it is time to clear the air.

One basic and irrefutable fact must be stated up front: No mount system is perfect for all situations! Any attempt to champion one mount scheme over another without considering all the facts is doomed to failure. Below are the true advantages and difficulties of the two most popular mounting system.

The Altazimuth
(i.e.: Dobsonian, etc.). This mounting system has gained considerable popularity over the past 20 years, evolving from the old 'pillar and claw' system originally used only in inexpensive small telescopes, to a modern well-designed one which boasts of supporting some of the largest apertures in amateur astronomy today.

Altazimuth Advantages

Altazimuth Disadvantages

Equatorial Mounts
These mounts are aligned to the celestial coordinate system and have been the mainstay of serious amateur and professional astronomical telescopes for over a century. They come in a variety of designs: German Equatorial, English Yoke, English Cross-axis, Polar disk, Fork, Split Ring, etc.

Equatorial Advantages

Equatorial Disadvantages

Note: none of these disadvantages will eliminate a mount design from use by the amateur. For strictly visual use (especially for the beginner), the altazimuth can easily be recommended, while for long-exposure photography, the equatorial is often the mount of choice. For very large apertures intended for easy portability, the altazimuth almost has to be used.

However, the compact split-ring equatorial design can also remain fairly portable even with telescopes as large as 18 inches. Computers and computerized driving systems have narrowed the choice between the two mounting systems (and driven up their prices), but their basic characteristics have not changed. In any case, both the altazimuth and the equatorial have a firm place in amateur astronomy.

This piece was written by David Knisely.

Binocular Telescopes

There have been some people who have built their own Binocular Telescope, this is two telescopes who are the same in every way that are mounted together and are used more or less like a pair of binoculars but are much more powerful. During the last few years a bino-viewer has been made that turns a normal scope into a bino-scope.

Now there is at least one company that is making and selling their own Binocular Telescope. While I have not been able to use such a scope (I don't have that kind of money!), I would think that the images from it would be awesome! They are SanJO Instruments.

What Accessories Will I Need?

In addition to a telescope, you absolutely must have a mounting and a tripod. You will also need a few eyepieces, a telescope with only one eyepiece is like a piano with one key.

These accessories don't come cheap, expect to pay as much for the mounting and tripod as you paid for the optical tube. For a first telescope, you probably will want to buy an entire system, it tends to be less expensive that way.

Which eyepieces should you start with? I'd suggest three or four, maybe a 30mm, 25mm, 20mm, 8mm and a 2x Barlow (which will give you coverage of 30,25, 20, 15, 12.5, 10, 8, and 4 mm). Buy eyepieces of like quality to your telescope. Putting a $300 Nagler eyepiece on a $150 telescope is pointless (it would also probably tip over the entire telescope).

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Author: Dennis Bishop

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FAQ Page One
FAQ Page Two
FAQ Page Three
FAQ Page Four
FAQ Page Five
FAQ Page Six
FAQ Page Seven
FAQ Page Eight
FAQ Page Nine

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