Telescopes Terminology

The Celestron 21063 AstroMaster 90 AZ Refractor Telescope is a popular example of astronomical optics.

Optical Formulas: Telescopes are described by a numerical representation such as 450x60mm. The first number is the maximum magnification (an object will appear 450 times closer than viewed with the naked eye) and the second number is the diameter of the objective lens (the closest to the object being viewed).

Penta Mirror Technology: Unlike conventional telescopes, this patented technology breakthrough allows for left to right correct views of the stars, not reversed. No more guessing which way to move the telescope. This feature provides unparalleled ease of use for finding and tracking objects with a convenient 90 degree viewing angle and 1.25″ eyepiece adapter.

Zoom Eyepiece Assembly: Astronomical and terrestrial viewers can zoom from 50x to 150x with no refocusing of the telescope. This feature allows for convenient magnification changes bringing the wonders of the night sky up close and personal with a twist of the power change ring.

Astronomical: Astronomical telescopes are designed specifically for observing heavenly bodies: stars, planets, moons, comets, etc. They are fitted with special features to stabilize the telescope and track the movement of stars and planets across the sky. They are very high powered, with magnifications of 40x to 600x depending on the model.

Finderscope: On most astronomical telescopes a lower powered finderscope with a wider field of view lets the user quickly locate the object to be viewed by the high magnification main telescope.

Barlow Lens: An auxiliary lens that increases the power by a factor. For example a 2x barlow would double the magnification of the telescope.

Eyepieces: In astronomical telescopes, interchangeable eyepieces are used to vary the magnification of the telescope.

Erecting Lenses: Lens used when viewing land based objects that correct the normally upside down and reversed image provided by an astronomical telescope.

Rotary Power® Turret: This patented feature allows for magnification and accessory changes to occur through a simple twist of the turret or accessory dial. Accessories are incorporated into the telescope so there are no loose parts, and magnification and accessory changes can be made instantaneously to suit viewing conditions.

Easy Track® Mount: Allows for quicker and easier setup and storage as well as reduces image shake caused by wind or ground tremors.

Related pages and posts: Choosing The Right Telescope, Telescopes.

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