How to Compare Refractor Telescopes

Comparing Mount Types

• 1

  Decide where you plan on using the telescope. This will determine whether you want to look at a tripod of a permanent pier for the telescope. A tripod offers less stability but more portability, while a pier mount is better for astrophotography.

• 2

  Look at the two types of mounts, altazimuth, and equatorial. The altazimuth mount is the simpler of the two. It allows for up and down and right to left motions, like the dial on a compass. An equatorial mount is aligned with the polar axis of the Earth, and tracks objects by moving one axis at a constant speed.

• 3

  Compare the different mount styles available. The Dobsonian mount is an altazimuth rocker mount that sits on the ground; it is often used for larger refractors to provide stability. The fork mount is an altazimuth mount used for smaller to medium-sized refractors. The German equatorial mount uses a T-Shape style for the declination and right ascension axis.

Calculating Magnification Limitations

• 4

  Find the focal length of the refractor. This is the larger of two numbers used to describe the size of the telescope. It is usually between 400 and 3,000 millimeters. It describes the distance from the lens at the top of the telescope to the mirror at the bottom.

• 5

  Find the size of the eyepiece. This will be a smaller number, usually less than 40 mm. At least one eyepiece is included with a telescope, but you can purchase many sizes.

• 6

  Divide the focal length number by the eyepiece number to get the magnification the telescope will provide with the eyepiece you put in it. Due to optical and atmospheric limitations, you should not use an eyepiece that will provide more than 50 times the aperture (which is basically the diameter of the end of the optical tube) in inches, or twice the aperture in millimeters.

• 7

  Compare the magnification number to the list of object you would like to view with the telescope. Close objects like the moon and planets will not need as much magnification as far-off objects like nebulae and galaxies .

Comparing Brands/Prices

• 8

  Check several companies for the type of refractor you have your eye on. There are many quality telescope companies in the market today, including large companies like Meade, Celestron and Orion.

• 9

  Compare the reviews and quality standards between the brands and narrow your search down.

• 10

  Compare the prices between brands. Check for the different features each company may offer. You may find that one will offer more of the size of refractor you want, or the style of mount you prefer.