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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 first of these was the Hamiltonian telescope patented by W. F. Hamilton in 1814. The Schupmann medial telescope designed by German optician Ludwig Schupmann near the end of the 19th century placed the catadioptric mirror beyond the focus of the refractor primary and added a third correcting/focusing lens to the system.
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 ...
The telescope is more a discovery of optical craftsmen than an invention of a scientist. [1] [2] The lens and the properties of refracting and reflecting light had been known since antiquity, and theory on how they worked was developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the ...
The next largest refractor telescopes are the James Lick telescope, and the Meudon Great Refractor. [1] Most are classical great refractors, which used achromatic doublets on an equatorial mount. However, other large refractors include a 21st-century solar telescope which is not directly comparable because it uses a single element non ...
Catadioptric telescopes, which use a combination of lenses and mirrors to form the image; essentially a combination of refracting and reflecting telescopes. Each type of telescope suffers from different types of aberration ; refracting telescopes have chromatic aberration , which causes colors to be shown on edges separating light and dark ...
This happened during testing of an 18.5-inch (470 mm) aperture great refractor telescope for Dearborn Observatory, which was one of the largest refracting telescope lens in existence at the time, and the largest telescope in the United States. [20] A 25-inch (63.5 cm) objective refractor was installed in the Newall telescope. [18]
He is also known for designing dialyte based refracting telescopes, coming up with the Zerochromat retrofocally corrected refractor, including a folded 30-inch f/12 version he built in 1999. This refracting telescope is the largest ever built by an individual and the eighth-largest refractor ever built. [3] Wall died on 27 January 2018.