Some Terms You Should Know: Telescopes

These are some terms you will come across in your lab class dealing with telescopes.
Eyepiece
In a telescope, the last lens before the viewer's eye.
Inverted Image
An image that is flipped upside down.
Magnification
A ratio of the size of an image to the size of the original object.
Objective Lens or Objective Mirror
In a telescope, the lens or mirror closest to the object being viewed.  This is the main optical piece of the telescope.
Reflector (or Reflecting Telescope)
A telescope that uses an objective mirror to gather in light and form an image.
Refraction
The bending of light rays, often done using a lens.
Refractor (or Refracting Telescope)
A telescope that uses an objective lens to gather in light and form an image.
Resolving Power
The ability of a telescope to resolve small detail in an image. This is dependent on the diameter of the objective lens or mirror.
Reverted Image
An image that is flipped left-to-right.


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 This page was last updated on 2 March 1998
and is © 1998 by Jim McDonald.