Hobbies And Interests
Home  >> Science & Nature >> Astronomy

How to Identify an 8-Inch Telescope

The most important feature of a telescope is its aperture, the diameter of the largest lens or mirror. Telescopes range in size (aperture) from the thickness of a cigar to the huge instruments housed in mountaintop observatories, including the Keck reflecting telescopes located at the summit of Mauna Kea in Hawaii, which have an aperture of about 33 feet, or 400 inches. Amateur telescopes generally have apertures less than about 25 inches, and the majority have apertures less than 8 inches. Most telescope's have their specifications -- the aperture and focal length -- etched or otherwise indicated somewhere on the optical tube assembly. A telescope's focal length is always greater than its aperture. The location of the specifications varies depending on the telescope type and manufacturer.

Instructions

  1. Newtonian Reflecting Telescope

    • 1

      Identify the telescope's focuser. This is the small tube assembly, near the open end of the optical tube, that holds the eyepiece. Two focuser wheels are located at the base of the assembly.

    • 2

      Note the numbers on or near the focuser assembly, or elsewhere on the optical tube. These numbers are the telescope's specifications, almost always given in millimeters. If only one number appears, it is probably the aperture.

    • 3

      Divide the aperture by the factor 25.4. The result is the aperture in inches.

    Catadioptric Telescope

    • 4

      Remove the cap on the front of the telescope's optical tube.

    • 5

      Note the telescope's specifications etched on the metal ring that secures the corrector plate (actually a large lens).

    • 6

      Divide the aperture by the factor 25.4. The result is the aperture in inches.

    Refracting Telescope

    • 7

      Examine the telescope's optical tube.

    • 8

      Note any conspicuous number, or two numbers, appearing on the tube. If only one number is found, it is probably the telescope's aperture in millimeters.

    • 9

      Divide the aperture by the factor 25.4. The result is the aperture in inches.

Astronomy
Astronomy

https://www.htfbw.com © Hobbies And Interests