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Celestron was the first large scale commercial manufacturer of the Schmidt-Cassegrain telescope, introducing its "C8" 8" diameter 2032 mm focal length, ƒ10 telescope in 1970. [7] The primary innovation Celestron/Tom Johnson devised was a method to produce Schmidt corrector plates using a vacuum to pull the glass blanks into a pre-shaped curve ...
The Celestron 8 was more compact, affordable and easier to manufacture than traditional telescopes, like the Schmidt–Cassegrain. [2] Johnson's new telescope proved very popular in the amateur astronomy and educational industries, allowing the hobby to rapidly expand and reach more consumers. [2] Johnson sold Celestron in 1980. [2]
Primary lens: The objective of a refracting telescope. Primary mirror: The objective of a reflecting telescope. Corrector plate: A full aperture negative lens placed before a primary mirror designed to correct the optical aberrations of the mirror. Schmidt corrector plate: An aspheric-shaped corrector plate used in the Schmidt telescope.
The FTC argued that an acquisition by Meade of Celestron would negatively impact the performance telescope market by eliminating significant competition between the two companies and by creating a monopoly in the market for Schmidt-Cassegrain telescopes, which were currently only being sold in the U.S. by Celestron and Meade.
Telescopes can be classified by optical design or mechanical design/construction. Telescopes can also be classified by where they are placed, such as space telescopes . One major determining factor is type of light, or particle being observed including devices referred to as "telescopes" that do not form an image or use optics.
Telescope History Archived 2021-02-14 at the Wayback Machine, NASA Official Website, accessed 02/09/2019 History of the Telescope , accessed 02/09/2019 List of astronomical observatories and telescopes , Encyclopedia Britannica, 02/09/2019
1917 – Mount Wilson 100-inch (2.5 m) optical reflecting telescope begins operation, located in Mount Wilson, California; 1918 – 1.8m Plaskett Telescope begins operation at the Dominion Astrophysical Observatory, Victoria, British Columbia, Canada; 1919 – International Astronomical Union (IAU) founded
Multiple mirror telescopes that are on the same mount and can form a single combined image are ranked by their equivalent aperture. Fixed altitude telescopes (e.g. HET) are also ranked by their equivalent aperture. All telescopes with an effective aperture of at least 3.00 metres (118 in) at visible or near-infrared wavelengths are included.