WHAT TYPE OF TELESCOPE SHOULD I BUY?

The type of telescope you buy depends on the amount of observing you are going to do.  Many good astronomers own several telescopes that are used for different tpes of observing although if you are a beginner you should start of with one telescope that you can use for different types of observing.
There are three basic types of telescopes:
Refractors - a lens is the primary device for gathering light.
Reflectors - a mirror is the primary device for gathering light.
Compound telescopes or catadioptrics - a combination of lenses and mirrors is used to gather light.
Below is table to help you choose the right type of telescope depending on your observing needs.

You should take into account where you would like to do most of your observing.  Refractors are good for lunar and planetary observing, while reflectors are good for deep-sky observing. Compound telescopes are good general observing instruments.

  • light-polluted urban skies - compound telescopes and refractors tend to do better than reflectors.
  • moderately light-polluted suburban skies - all types tend to be equal.
  • dark, rural skies - compound telescopes and reflectors tend to be slightly better than refractors because they are better able to collect light.

 

Optical Features

Optics are important in the use of telescopes because they collect the light.  Poor optics make it difficult to see things clearly.

When buying a new telescope you need to consider the things below:

  • Aperture
  • Magnification
  • Focal length
  • Focal ratio (f/number)
  • Wave number
  • Resolution

How powerful should my telescope be?

Power is not the most important factor of a telescope. The magnification or power does not have a lot to do with the optical performance of the telescope. The magnification can be as high as you want it to be but without the proper lenses it will not work very well.

What type of telescope would be good for a child?

Before buying a telescope take your family outside of an evening and get to know the sky and the consellations and planets that you can see.

Some good telescopes for children:

  • Small refractors - many children like to see the moon and planets. These telescopes provide good views of these objects.
  • Rich-field reflectors - these telescopes provide bright, low-power, wide-field images of many types of objects. They are usually easy to aim, and the wide-field view makes them easy to use when searching for objects.

Children need a light telescope and one that is easy to set up and put down.

  • The mount should be not be too high for a child, so he or she can view through the eyepiece while standing.
  • The mount should be sturdy so that it does not vibrate.
  • The mount should have a low center of gravity so that it does not tip over easily.

Their first telescope could be one of many so buy one that is easy to use.

How much does a telescope cost?

Prices of telescopes vary depending on the type.  The start at approximately $200 and can go up to $20,000 or more.

  • small Newtonian reflectors (6 inches or less aperture) - $250 to $1,000
  • achromatic refractors (2-3 inch aperture) - $250 to $1,000
  • large Dobsonian reflectors (6-18 inch apertures) - $300 to $2,000
  • compound telescopes (6-11 inch aperture) - $1,000 to $3,000
  • apochromatic refractors (3-5 inch aperture) - $2,000 to $10,000

What does a finderscope do?

Finderscopes are used to aim the telescope at an object.  Finderscopes come with some telescopes but on some you need to purchase them.

Finders can come in three basic types:

  • peep sights - notches or circles that allow you to line up the target.
  • reflex sights - a mirror box that shows the sky and illuminates the target with a red LED diode spot similar to a laser sight on a gun.
  • telescope sight - a small, low magnification (5x to 10x) telescope mounted on the side with a cross hair reticle, like a telescopic sight on a rifle; unlike the other two finders, this type presents an upside-down image to your eye.

What do I need to take a picture of the moon, planets and stars?

Photos can be taken through a telescope of piggy backed on a telescope with special mounts and adaptors. You can use a normal camera, a video camera or a DSLR camera. This is called astrophotography.

To take photos through the telescope you will need the following:

  • 35-mm camera (with manual capability), video camcorder, or DSLR 
  • camera or "T" adapter
  • manual cable release for 35-mm camera
  • off-axis guider