Types of Telescopes

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 Telescope Types


 

 What are those numbers?


The f-ratio is the focal length divided by the diameter of the telescope. Magnification is the focal length of the telescope divided by the focal length of the eyepiece.

Example:

To find the f-ratio of a telescope 10 " in diameter with a 45" focal length:

    • Divide 45 " F.L. by10" D. to get an f-ratio of 4.5.

To compute magnification:

First, convert focal length to mm: 45" = 1146 mm, then:

    • 1146 mm focal length divided by 35 mm eyepiece equals 33 magnification.