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Choosing and Using a Telescope

Updated on September 2, 2015

Year of Astronomy Coin

Year of Astronomy Coin
Year of Astronomy Coin | Source

Choosing a Telescope

What telescope you choose depends on what it will be used for, and what you expect to get out of it. There are many types of telescopes, and the choice of what is best may change over time as you become more or less involved in astronomy. Amateurs often start with a curiosity, which can be served by a telescope that is not suitable to a professional astronomer. Yet, they can provide some entertaining evenings.

Different telescopes have different purposes.

Intro Image: Perth Mint

2010 Was The International Year of Astronomy

The image used for this lens depicts the Perth Mint's coin for the International Year of Astronomy. The telescope represents Galileo's telescope.

Refractor Telescopes

The first telescopes were undoubtedly refractor telescopes. In a refractor telescope, converging lenses are used to magnify distant objects. They work much like long magnifying glasses. Light from distant stars and galaxies is gathered and magnified using converging lenses. The observer looks through a lens at the light, and sees distant objects magnified.

Refractor telescopes often have aberration problems. Colors bend as slightly different angles when entering and leaving a lens. This causes a minor separation of colors, which often results in colors showing at the edges of objects. This can be corrected with additional lenses, but every time light goes into a lens, and more so when it exits a lens, light is lost due to a reflection. Additionally, light reflecting twice in a lens will exit in the wrong place, so there will still be a minor problem.

The lens at the front of the telescope reverses the image, so up is down and right is left. Again, an additional lens can correct this, but will cause the same problems as mentioned above.

Reflector Telescopes

Reflector telescopes are able to gather to light, and focus the light on a mirror.. The mirrors are curved, and cause no aberrations. The problem is the mirrors must be exactly placed. Mirrors do not add to the aberrations if curved properly, and can even provide a truer image. Magnifying power is greater for a reflector telescope than for a same size lens refractor telescope. This makes smaller and more easily handled reflectors abke to magnify as much as a much larger refractor.

Astronomy for Dummies

Catadioptric telescopes

These are relatively short telescopes that can gather light from a wider field. They are made as combinations of refractor and reflector telescopes. They give a wider field of view, which can be significant to amateur astronomers.


Eyepieces can either be mounted directly in line or at right angles with the telescope. At right angles it would probably have a prism reflecting the light, since less light would be lost.

Tracking Motors

The Earth is rotating. As it rotates, objects in the sky appear to move. If you wish to keep the object in the field of view for any amount of time, use a tracking motor. It you really need the object to appear to be stationary, as you would for photography, use a tracking motor. Light from stars is so faint, especially if the light is magnified, that time exposure is required for good photography.

Where Should You Go with Your Telescope?

First, get away from all street lights. Stray light from street lights can be scattered so as to make the background too bright. You need to be in the dark.

To avoid strange things like twinkling of stars, get above as much of the atmosphere as possible. Did you ever see wavy images when you look through a heated air column, like air rising from a chimney. The atmosphere has the same effect. Imagine how much air you are looking through from the surface of the Earth. Reduce it for better results. Many of the large research telescopes are located on mountains.

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    • Ardyn25 profile image

      Ardyn25 5 years ago

      My son just got a telescope and I'm interested in exploring. I like the different types you offered and i'm thinking we need to upgrade. Thank you.

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      anonymous 5 years ago

      Before reading this, I really did not know there is so much to the telescope. My, it has greatly advanced since Galileo used it to examine the stars.

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      anonymous 6 years ago

      Your lens is best destination for choosing perfect telescope which we want.Thanks for sharing these wonderful information.


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      twinklingSkies 6 years ago

      Nice post. And what about Catadioptric telescopes like Schmidt-Cessegains? These are also rather popular on Amazon or eBay.

    • jlshernandez profile image

      jlshernandez 6 years ago

      We have a telescope somewhere in the storage shed as it was too large to keep in the house. It is one of those that slowly rotate with the earth. My brother who is an astroinomy buffset it up once on our driveway and we saw Jupiter with its straited pattern. It was prtty cool. Now I am curious about the telescope after reading this lens. Thanks for sharing all the valuable tips.

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      GetSillyProduct 6 years ago

      great resource for picking a telescope. This will be really handy for me when I purchase my first!

    • Jhangora LM profile image

      Jhangora LM 6 years ago

      Thanx a lot for such a wonderful resource on Telescopes!

    • PNWtravels profile image

      Vicki Green 6 years ago from Wandering the Pacific Northwest USA

      We have a telescope that I enjoy using but I don't even know what kind it is. I guess your lens made me aware of the fact that I have a lot to learn about telescopes and astronomy!

    • cire81 lm profile image

      cire81 lm 6 years ago

      Good lens, can see your hardwork and effort. Keep up the effort.