We Know: Telescopes: 1-Minute Lesson

What is a telescope?

Telescopes are instruments used to help you see objects at a distance and are usually used for viewing the sky (astronomy) or land (terrestrial). A telescope allows you to see details at a distance mostly by collecting light (as opposed to magnification.)

The telescope collects light through a lens or a mirror. The better the telescope is at collecting light, the better you are able to see the details of what you are looking at in the distance.

How many types of telescopes are there?

There are 3 basic kinds:

Refracting telescopes use an objective lens to collect light.
Reflecting telescopes use a mirror to collect light.
Catadioptric telescopes use both mirrors and lenses to collect light.

What is the purpose of the eyepiece?

While the telescope collects light and focuses the object you are viewing, the function of the eyepiece is to magnify the object.

A high-power eyepiece is usually about 4 mm. A low-power eyepiece is usually about 40 mm in length.

What kind of telescope should I buy if this is my first?

If you're going to use the telescope for viewing both land and sky objects, then manufacturers often suggest a refracting (lens) telescope or catadrioptric telescope (mirror and lens).

If you're going to use the telescope for mostly astronomy, then you should consider a reflecting (mirror) or catadrioptric (mirror and lens) telescope.

What's a good guideline in selecting a first telescope?

Try to buy the largest aperture (diameter) telescope you can afford. Remember, this is a measure of how much light the telescope can collect. The power of the telescope does NOT tell you how much you will see, and is not nearly as important as the diameter of the telescope's main lens or mirror.

A reflecting telescope usually gives you the largest aperture for your money.

What kind of options come with telescopes?

Here are some common options:

Eyepieces - Once you buy the telescope, you can purchase a variety of different eyepieces for most telescopes. For example, low-powered wide- field eyepieces are good for viewing land, while high-powered eyepieces are good for seeing details on the moon.
Mounts - for holding your telescope in place.
Camera adapters - allow you to take pictures of what you see through the telescope.
Manual and computerized tracking devices - help you follow the object you are observing even as it continues to move.

How much does a good beginning telescope cost?

You can buy a good beginner's telescope, such as one from the Meade NG series, for about $80-120.

Who makes telescopes?

Manufacturers include Meade, Bushnell, Celestron, Televue, and Tasco.