Scope out $85 off the Celestron AstroMaster 130 EQ telescope

Feb 21, 2023
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The Celestron AstroMaster 130 EQ utilizes a flat spherical 130mm/5.11 in primary mirror [flat, NOT parabolic]. Screwed into the end of the focuser drawtube that extends inside the telescope is an "image corrector lens". This compensates for spherical abberation since the telescope has a flat spherical mirror instead of a parabolic mirror. "The corrector extending the focal length in a "telephoto" type layout." In order to collimate the primary and secondary mirror properly, the "image corrector lense" that is screwed into the end of the focuser draw tube must be removed. After collimating, reinstall the "image corrector lense". This optical design is known as a "Bird-Jones" or sometimes called a "Jones-Bird" optical design.
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