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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 ...
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 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]
Tour guide points out the double Finderscope on the 24.5 inch Cassegrain Telescope at the Goldendale Observatory State Park. A finderscope is an accessory sighting device used in astronomy and stargazing, typically a small auxiliary refracting telescope/monocular mounted parallelly on a larger astronomical telescope along the same line of sight.
Ever since Galileo Galilei adapted a Dutch invention for astronomical use, astronomical telescope making has been an evolving discipline. Many astronomers after the time of Galileo built their own telescopes out of necessity, but the advent of amateurs in the field building telescopes for their own enjoyment and education seems to have come into prominence in the 20th century.
Telescope mounts are designed to support the mass of the telescope and allow for accurate pointing of the instrument. Many sorts of mounts have been developed over the years, with the majority of effort being put into systems that can track the motion of the fixed stars as the Earth rotates .
Space telescope: instrument in space to study astronomical objects; Spectrometers: used to measure spectral components of light; Sundial: device that tells the time of day by the apparent position of the Sun in the sky; Transit instrument: small telescope used for precise astrometry
For an equatorial GoTo telescope mount, the user must align the mount by hand with either the north celestial pole or the south celestial pole. Assuming the user is accurate in the alignment, the mount points the telescope to a bright star, asking the user to center it in the eyepiece.