Chapel Hill Astronomical and Observational Society
Telescopes 101 Print E-mail

Telescopes 101

There are basically 2 types of telescopes:


Refracting Telescopes (often called refractors).  These telescopes gather light in the Objective (also called primary) and focus it using a series of lenses inside the telescope.  These are popular with new telescope buyers because they "look like telescopes" and many low end telescopes are of this time.

 

 

 

Reflecting Telescopes (often called reflectors).  These telescopes gather light in the Objective (also called primary) mirror and bounce that light to an eyepeiece with the secondary mirror.

 

 

 

 

General Advice

  • You get what you pay for
  • reflectors provide more value for the money, especially in lower end telescopes
  • a poor quality mount will make even the best telescope perform poorly

Things to Consider:

  • Power This is a question asked by many new telescope buyers but it's not one that amateur astronomers really think about.  Telescopes are measured not by their magnification power but by their aperture, or the diameter of the opening where light enters the telescope.  The larger the aperture, the more you'll be able to see in general.
  • Portability dont discount this.  The best telescope for you is the one you'll use regularly.  Dobsonian telescopes are relatively inexpensive and very stable.  They aren't the most portable though.  If you camp, consider a model that fits in a backpack.  Even a small telescope can get great views in the woods away from the light pollution.
  • Accessories You may want to add more eyepeices, or other accessories like a telrad to help you easily aim your new telescope.

Things to avoid in a new telescope

  • Telescopes sold in a store that doesn't normally sell telescopes (discount stores, drug stores, even camera stores).
  • Boxes with beautiful photos of planets and nebulae, those photos probably came from the Hubble Space Telescope. That $30 telescope cant produce images that clear.  NASA had to put the telescope above Earth's atmosphere to get photos that clear and then process them by experts.
  • lightweight tripods
  • low-cost go-to telescopes.

So what should I buy

  • If you have less than $100 to spend, look for a tabletop model from a notable manufacturer such as the Celestron First Scope or Orion FunScope.
  • If you have $100 - $300 a Newtonian telescope with a tripod.  All
  • $300-$500 a 4"-6" Dobsonian telescope
  • $500+ a 6"-8"+ Dobsonian telescope
  • $1000+ lots more to consider here, best to email below and ask some more specific questions

Further resources:

Have a question?  Volunteers from CHAOS and the Raleigh Astronomy Club will answer them, email:

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Images courtesy Canadian Science and Technology Museum