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Barlow lens: Optical element to increase the telescope's focal length and magnification, narrow the field of view and reduce coma distortion, providing opposite effects of a telecompressor. Astronomical filter: Used to select specific colors (or light frequencies) for astrophotography.
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 ...
A diagram of the electromagnetic spectrum with the Earth's atmospheric transmittance (or opacity) and the types of telescopes used to image parts of the spectrum. Visible-light astronomy encompasses a wide variety of astronomical observation via telescopes that are sensitive in the range of visible light ( optical telescopes ).
In the amateur astronomy field, many types of commercial and amateur built telescopes are designed for astrophotography and labeled "astrographs". Optical designs of amateur astrographs vary widely but include apochromatic refractors, variations of Cassegrain reflectors, and Newtonian reflectors.
Newtonian telescope design. A Newtonian telescope is composed of a primary mirror or objective, usually parabolic in shape, and a smaller flat secondary mirror.The primary mirror makes it possible to collect light from the pointed region of the sky, while the secondary mirror redirects the light out of the optical axis at a right angle so it can be viewed with an eyepiece.
Diagram of Schmidt camera The 77 cm Schmidt-telescope from 1966 at Brorfelde Observatory was originally equipped with photographic film, and an engineer is here showing the film-box, which was then placed behind the locker at the center of the telescope (at the telescope's prime focus)
Diagram of the lightpath through a Gregorian telescope. The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke. James Gregory was a contemporary of Isaac Newton, and both often worked simultaneously on similar projects.
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 .