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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 .
The main material used early on for reflecting telescope mirrors was speculum metal, which reflected only about two-thirds of the incident light, and which tarnished, requiring maintenance. Two-element refracting telescopes were extensively used in 19th century observatories despite their smaller apertures than metal, and later glass, mirror ...
Telecompressor or focal reducer: Optical element to decrease the telescope's focal length and magnification (usually by a fixed percentage) and widen the field of view, providing opposite effects of a Barlow lens. Star Diagonal: Used to change the angle of the light coming out of a telescope, for easier viewing.
The Swedish 1-m Solar Telescope, with a lens diameter of 43 inches, is technically the largest, with 39 inches clear for the aperture.The second largest refracting telescope in the world is the Yerkes Observatory 40 inch (102 cm) refractor, used for astronomical and scientific observation for over a century.
An Achromatic telescope uses an achromatic lens to correct for this. An achromatic lens is a compound lenses made with two types of glass with different dispersion. One element, a concave lens made out of Flint glass, has relatively high dispersion, while the other, a convex element made of Crown glass, has a lower dispersion. The crown lens is ...
This had an objective made by the makers Chance, with the overall telescope made by Thomas Cooke. [21] The telescope was made for Robert Stirling Newall, and when completed in 1869 was the largest refracting telescope in the world. [21] In the 1950s the University of Cambridge donated the Newall telescope to the National Observatory of Athens ...
NASA's James Webb Space Telescope (JWST) has captured photos of one of the earliest supernovas ever seen, with features appearing like grains and knots found in a cut of wood. "Once upon a time ...
A drawing of the telescope from an astronomy book. The fabrication of the two-element achromatic objective lens, the largest lens ever made at the time, caused years of delay. [2] The famous large telescope maker Alvan Clark, was in charge of the optical design. He gave the contract for casting the high quality optical glass blanks, of a size ...
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