Selecting a Telescope

by Michael Frasca





The Five Cardinal Rules

  1. Never buy a "Department Store Refractor".
  2. The best telescope to buy is the one that will be used.
  3. Never buy a "Department Store Refractor".
  4. A telescopes' use is inversely proportional to its size.
  5. Never buy a "Department Store Refractor".

Characteristics of a Telescope

Types of Optics

  • Refractor
  • Reflector
  • Compound
  • Aperature

The diameter of the lens or primary mirror. Determines how much light is gathered and the amount of detail seen.


  • Altitude-azimuth
  • Equatorial

Type of Optics


  • Most expensive per inch of aperature.
  • Best views of planets, moons and sunspots.
  • Direct view of astronomical objects
  • Prone to chromatic abberation


  • Least expensive per inch of aperature.
  • Works best with an alt-az mount.
  • A good all-around telescope.
  • Some models require accurate colimation.
  • May require periodic cleaning of mirror
    and re-aluminizing


  • Schmidt-Cassigrain or Maksutov-Cassegran
  • Very compact
  • Works well with an Equatorial Mount
  • Best for astrophotography.
  • Mirror moves as telescope is focused,
    may cause mirror shift
  • Secondary mirror obstructs 20-30% of light path

Types of Telescope Mounts


  • "Alt-Az" or "Dobsonian".
  • Very simple and sturdy.
  • Requires hand guiding to follow an object.
  • find objects by star-hopping.
"Dobsonian" mounts
  • Easy to setup
  • Easy to Point
  • Inexpensive


  • Telescope will follow an object.
  • Must be aligned with Polaris to work.
    (Northern hemisphere)
  • More expensive and not as sturdy.
  • Photography


  • Two refractors connected together.
  • Less expensive than telescope.
  • Described in terms of magnification X aperture in centimeters.
  • Look for 7X35, 7X50, or 10X50.
  • Can be used for activities other than astronomy.

Some Specific Recommendations

Under $200

  • Bushnell 7X35 Binoculars - About $150.00.
  • Orion 7X50 Explorer - $200.

Around $300

  • Meade Starfinder about $320.
    • 6 inch reflector
    • Easy to setup and use.
    • Alt-Az mount
    • Get the $50.00 accessory package which includes 2 additional eyepieces.
  • Edmund Astroscan about $315.
    • 4 inch reflector
    • Durable and easy to use.
    • Ideal for very young children.

Under $600

  • Meade ETX 90mm Maksutov-Cassigrain about $595.
    • Lightweight (about 9 lbs)
    • Clock-drive
    • Alt-Az Mount
    • Can be used for terristrial viewing (optional)

Around $1000

  • Celestron C5+ about $1199
    • Schmidt-Cassegrain compound optics.
    • DC RA Drive and Hand Control
    • Table-top equatorial mount.
    • Compact and portable.
    • Tripod costs around $289


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