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Which Telescope Should I Buy?
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Which Telescope Should I Buy?

The decision on which telescope to buy is difficult to make if you have not used a telescope before. Here is what I have learned.

Choosing a Telescope

For a good explanation of telescope basics go to Celestron International

Always choose the brand with the best optics. A cheap telescope is not going to have good optics.

First of all you need to know what and who it is intended to be used for.

Is it for use by a child <14 years old? A young child will not understand how to setup and maintain a complicated telescope. It is best to buy them a small telescope. A 60mm refractor is ideal.

Is it for use by an adult who is only occasionally going to look at the sky and perhaps terrestrial objects?. For casual observing of the night sky and terrestrial objects, a 60mm to 90mm refractor or 60mm to 90mm Maksutov are ideal.

Is it for use by an adult who wants to seriously observe the night sky and perhaps join an astronomy club. For more advanced use, a 150mm to 200mm reflector or 80-100mm refractor is the ideal choice. If it is not going to be used for astrophotography, a Dobsonian Mounted Newtonian is ideal. Otherwise, get a equatorial mount with 80-100mm refractor or 150mm to 200mm reflector, such as a Schmidt-Cassegrain or Newtonian.

Is it for use by an adult who has advanced knowledge of amateur astronomy and who wants to do astrophotography? Well, in this case, a telescope with more aperture is in order. The smallest telescope worth considering is a 200mm reflector or 100mm refractor, although the aperture largely depends on what the telescope will be used for. For widefield, 70-80mm f/6-f/7.5 refractors and 150mm-200mm f/5 Newtonians are popular. For planetary work, a 250mm or larger Newtonian or 200-300mm SCT telescope is required. The telescope requires an equatorial mount with dual axis drives and autoguider port for astrophotography. A Newtonian telescope is the lowest cost and has the least light obstruction and gives the brightest images but requires a very solid equatorial mount, which becomes impractical in the larger sizes. For portability and excellent optics, a Schmidt-Cassegrain telescope is an excellent option. A 80mm to 100mm or larger apo-refractor is a nice wide field telescope, requires very little maintenance and is also quite portable. Ritchey Chretien (RC) telescopes are usually the choice of advanced astrophotographers who use dedicated CCD Astro cameras.

Pros and Cons of the Various Telescopes
	Pros	Cons
Refractor	Low Maintenance, Portable, ED Varieties with High Resolution. Usually Relatively Coma Free	Limited to Small Apertures,
Newtonian	Low Cost, Large Apertures, Bright Images	High Maintenance, Not Very Portable, Exhibit Coma
SCT	Portable, High Magnification, Large Apertures, Low Maintenance, High Resolution, Usually Relatively Coma Free	High Cost.
Maksotov	High Optical Quality, Portable, Low Maintenance, High Magnification	Restricted to Apertures <200mm Due to High Cost, Narrow Field of View
RC	Free from Optical Aberrations (Coma Free), Portable in Smaller Sizes, Large Apertures, High Resolution	Very High Cost. Used for Photography

Accessories

In addition to the main telescope assembly, you will require the following accessories:

10mm and 25mm plossl eyepieces
2x shorty Barlow
Collimating eyepiece for reflectors
Red light torch
Software or sky charts for locating objects in the sky
Scope cover