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A Ritchey–Chrétien telescope (RCT or simply RC) is a specialized variant of the Cassegrain telescope that has a hyperbolic primary mirror and a hyperbolic secondary mirror designed to eliminate off-axis optical errors (coma). The RCT has a wider field of view free of optical errors compared to a more traditional reflecting telescope ...
List of largest optical refracting telescopes. The Grande Coupole for the double refractor of Meudon, with roughly 83 cm (33 in) and 62 cm (24 in) aperture lenses on the same mounting, and making its debut in 1891. Refracting telescopes use a lens to focus light. The Swedish 1-m Solar Telescope, with a lens diameter of 43 inches, is technically ...
40-foot telescope. William Herschel 's 40-foot telescope, also known as the Great Forty-Foot telescope, was a reflecting telescope constructed between 1785 and 1789 at Observatory House in Slough, England. It used a 48-inch (120 cm) diameter primary mirror with a 40-foot-long (12 m) focal length (hence its name "Forty-Foot").
36 × 1.8 m hexagons M1 mirror: Segmented mirror, M1 f/1.75: 4145 1976–1993: BTA-6: 6: 26: 605 cm f/4 M1 mirror: Mirror replaced twice: 2070 1948–1976: Hale (200 inch) 5.1 – 508 cm f/3.3 M1 mirror: Art deco dome: 1713 1917–1948: Hooker (100 inch) 2.54 – Also used for 1st optical interferometer: 1742 For earlier entries, see List of ...
24-inch convertible Newtonian/Cassegrain reflecting telescope on display at the Franklin Institute. A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an ...
Refracting telescope. A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses.