long-focal length telescope

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• Focal length — The focal length of an optical system is a measure of how strongly it converges (focuses) or diverges (diffuses) light. A system with a shorter focal length has greater optical power than one with a long focal length. Thin lens approximation For… …   Wikipedia

• telescope — /tel euh skohp /, n., adj., v., telescoped, telescoping. n. 1. an optical instrument for making distant objects appear larger and therefore nearer. One of the two principal forms (refracting telescope) consists essentially of an objective lens… …   Universalium

• History of the telescope — The earliest known working telescopes appeared in 1608 and are credited to Hans Lippershey and Zacharias Janssen, spectacle makers in Middelburg, and Jacob Metius of Alkmaar. The design of these early refracting telescopes consisted of a convex… …   Wikipedia

• Reflecting telescope — 24 inch convertible Newtonian/Cassegrain reflecting telescope on display at the Franklin Institute. A reflecting telescope (also called a reflector) is an optical telescope which uses a single or combination of curved mirrors that reflect light… …   Wikipedia

• Schmidt-Cassegrain telescope — The Schmidt Cassegrain is a catadioptric telescope. It combines a folded optical path with a corrector plate to make a compact astronomical instrument. Invention and DesignThe Schmidt Cassegrain is a design based on Bernhard Schmidt s Schmidt… …   Wikipedia

• Achromatic telescope — The achromatic telescope is a refracting telescope that uses an achromatic lens to correct for chromatic aberration. How it worksWhen an image passes through a lens, the light is diffracted at different angles for different wavelengths. This… …   Wikipedia

• astronomical telescope — noun any telescope designed to collect and record electromagnetic radiation from cosmic sources • Hypernyms: ↑telescope, ↑scope • Hyponyms: ↑optical telescope, ↑radio telescope, ↑radio reflector * * * noun : a telesco …   Useful english dictionary

• astronomical telescope — a telescope having an objective with a long focal length and an eyepiece with a short focal length, usually used for observing celestial bodies. Also called Kepler telescope. [1880 85] * * * …   Universalium

• Galilean telescope — a refracting telescope that forms an erect image, consisting of an objective of relatively long focal length that causes light rays to converge and an eyepiece of short focal length that causes them to diverge. [1715 25] * * *       instrument… …   Universalium

• Optical telescope — Eight Inch refracting telescope (Chabot Space and Science Center) An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for… …   Wikipedia

• Refracting telescope — A refracting or refractor telescope is a dioptric telescope that uses a lens as its objective to form an image. The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used in other devices such… …   Wikipedia