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Encyclopedia > Schmidt camera
Optical ray paths inside Schmidt camera
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Optical ray paths inside Schmidt camera
2m Schmidt Camera (Alfred-Jensch-Telescope Tautenburg, Thuringia, Germany
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2m Schmidt Camera (Alfred-Jensch-Telescope Tautenburg, Thuringia, Germany

A Schmidt camera is an astronomical camera designed to provide wide fields of view with limited aberrations. Other similar designs are the Wright Camera and Lurie-Houghton telescope. Image File history File links Schmidt-Teleskop. ... Image File history File links Schmidt-Teleskop. ... Image File history File links Download high resolution version (650x930, 68 KB) Please see the file description page for further information. ... Image File history File links Download high resolution version (650x930, 68 KB) Please see the file description page for further information. ... The Republic of Thuringia (German: Freistaat Thüringen) lies in central Germany and is among the smaller of the countrys sixteen Bundesländer (federal states), being eleventh in size with an area of 16,200 km² and twelfth most populous with 2. ... A giant Hubble mosaic of the Crab Nebula, a supernova remnant. ... A camera is a device used to take pictures (usually photographs), either singly or in sequence, with or without sound recording, such as with video cameras. ... The field of view is the part of the observable world that is seen at any given moment. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Contents

Invention and design

The Schmidt camera was invented by Bernhard Schmidt in 1930[1]. Its optical components are an easy to make spherical primary mirror, and an aspherical correcting lens, known as a corrector plate, located at the center of curvature of the primary mirror. The film or other detector is placed inside the camera, at the prime focus. The design is noted for allowing very fast focal ratios, while controlling coma and astigmatism. Bernhard Schmidt (March 30, 1879–December 1, 1935) was an Estonian-born optician who lived in Germany. ... 1930 (MCMXXX) was a common year starting on Wednesday (link is to a full 1930 calendar). ... A sphere (< Greek σφαίρα) is a perfectly symmetrical geometrical object. ... A primary mirror is a form of distributed data management on the Internet. ... A lens. ... A Schmidt corrector plate, invented by Bernhard Schmidt in 1931, is a lens used to correct spherical aberration in a reflecting telescope that uses a spherical primary mirror. ... A 35mm lens set to f/11, as indicated by the white dot above the f-stop scale on the aperture ring In photography the f-number (focal ratio) expresses the diameter of the diaphragm aperture in terms of the effective focal length of the lens. ... In optics (especially telescopes), the coma in an optical system refers to monochromatic aberration inherent to certain optical designs or due to imperfection in the lens or other components which results in off-axis point sources such as stars appearing distorted. ... Astigmatism is a refraction error of the eye in which there is a difference in degree of refraction in different meridians. ...


Schmidt cameras have very strongly curved focal planes, thus requiring that the film, plate, or other detector be correspondingly curved. In some cases the detector is made curved; in others flat media is mechanically conformed to the shape of the focal plane through the use of retaining clips or bolts, or by the application of a vacuum. A field flattener, -in its simplest form, a planoconvex lens in direct contact with the film- is sometimes used. Systems with such lens are called Schmidt-Väisälä camera. The focal plane of a lens is a plane that is perpendicular to the axis of the lens and passes through its focus. ... Look up Vacuum in Wiktionary, the free dictionary. ... This is a variant of Schmidt cameras that are special astronomical telescopes intended for wide-field photographic work. ...


Applications

The Schmidt camera is typically used as a survey instrument, for research programs in which a large amount of sky must be covered. These include astronomical surveys, comet and asteroid searches, and nova patrols. Comet Hale-Bopp For other uses, see Comet (disambiguation). ... 253 Mathilde, a C-type asteroid. ... Artists conception of a white dwarf star accreting hydrogen from a larger companion A nova (pl. ...


In addition, Schmidt cameras and derivative designs are frequently used for tracking artificial earth satellites. MILSTAR:A communication satellite A satellite is any object that orbits another object (which is known as its primary). ...


Starting in the early 1970s, Celestron marketed an 8-inch Schmidt Camera. The camera was focused in the factory and was made of materials with low expansion coefficients so it would never need to be focused in the field. Early models required the photographer to cut and develop individual frames of 35mm film as the film holder could only hold one frame of film. About 300 Celestron Schmidt Cameras were produced. The 1970s decade refers to the years from 1970 to 1979, inclusive. ... Celestron is a company that makes and imports telescopes, binoculars, spotting scopes, microscopes, and accessories for their products. ...


The Schmidt system was popular, used in reverse, for television projection systems. Large Schmidt projectors were used in theaters but systems as small as 8-inches were made for home use and other small venues. A video projector takes a video signal and projects the corresponding image on a projection screen using a lens system. ...


Arguably the most famous and productive Schmidt camera is the Oschin Schmidt Telescope at Palomar Observatory. It was used for the National Geographic Society - Palomar Observatory Sky Survey (POSS), the POSS-II survey, the Palomar-Leiden (asteroid) Surveys, and other projects. The telescope used in the Lowell Observatory Near-Earth-Object Search (LONEOS) is also a Schmidt camera. The Samuel Oschin telescope is a 48-inch (1. ... Palomar Observatory is a privately-owned observatory located in San Diego County, California, 90 miles (145 km) southeast of Mount Wilson Observatory, on Palomar Mountain. ... The National Geographic Society - Palomar Observatory Sky Survey (NGS-POSS) is a major photographic survey of the night sky completed at Palomar Observatory in 1958. ... Lowell Observatory Near-Earth-Object Search (LONEOS) is a program run by NASA and Lowell Observatory in Flagstaff, Arizona, to discover near-Earth objects. ...


Derivative designs

Lensless Schmidt

Prior to Schmidt's design, the solution to spherical aberration was to place an aperture stop at the center of curvature of the mirror, stopping the aperture to f/10. This removes spherical aberration while preserving the wide field of the short focal-length mirror. However, it does so at the cost of light-gathering ability. Although this solution was well-known long before Bernhard Schmidt invented his corrector plate, the design is known as a "lensless Schmidt".


Schmidt-Väisälä

Contemporary to Bernhard Schmidt's Schmidt camera design, but unpublished was also Prof. Yrjö Väisälä's identical design which he had mentioned in lecture notes in 1924 with a footnote: "problematic spherical focal surface". Once he saw Schmidt's publication, he promptly went ahead and solved the field flattening problem by placing a doubly-convex lens slightly in front of the film holder. This resulting system is known as: Schmidt-Väisälä camera or sometimes as Väisälä camera. Bernhard Schmidt (March 30, 1879–December 1, 1935) was an Estonian-born optician who lived in Germany. ... Yrjö Väisälä (IPA: ) (September 6, 1891 - July 21, 1971) was a Finnish astronomer and physicist. ... This is a variant of Schmidt cameras that are special astronomical telescopes intended for wide-field photographic work. ...


Baker-Schmidt

In 1940, James Baker of Harvard University modified the Schmidt camera design to include a convex secondary mirror, which reflected light back toward the primary. The photographic plate was then installed near the primary, facing the sky. This variant is called the Baker-Schmidt camera. Dr. James Gilbert Baker (November 11, 1914–June 29, 2005) was an American astronomer and optician. ... Harvard University (incorporated as The President and Fellows of Harvard College) is a private university in Cambridge, Massachusetts. ...


Baker-Nunn

The Baker-Nunn design, by Dr. Baker and Joseph Nunn, replaced the Baker-Schmidt camera's corrector plate with a small triplet corrector lens closer to the focus of the camera. A dozen Baker-Nunn cameras with 20-inch aperatures – each weighing 3.5 tons – were used by the Smithsonian Astrophysical Observatory to track artificial satellites from the late 1950s to mid 1970s.[1] Joseph Nunn (1905–1968) was an American engineer. ... The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). ...


Mersenne-Schmidt

The Mersenne-Schmidt camera consists of a concave paraboloidal primary mirror, a convex spherical secondary mirror, and a concave spherical tertiary mirror.


Schmidt-Newtonian and Schmidt-Cassegrain

The addition of a flat secondary mirror at 45° to the optical axis of a Schmidt camera creates a Schmidt-Newtonian telescope. The addition of a convex secondary mirror directing light through a hole in the primary mirror creates a Schmidt-Cassegrain telescope. These two designs are popular with telescope manufacturers because they are compact and use simple spherical optics. A secondary mirror (or secondary) is a second light gathering and focusing surface in a reflector telescope. ... The optical design of this telescope combines elements from both the Schmidt camera and the Newtonian telescope. ... A Schmidt-Cassegrain Telescope, invented by Bernhard Schmidt, is a catadioptric telescope. ...


Notes, references

  1. ^ http://www.satobs.org/seesat/Nov-1996/0036.html

External link


  Results from FactBites:
 
Schmidt camera: Information from Answers.com (1101 words)
Schmidt optics are often used in microscopes, astronomical spectrographs, and projection televisions.
Schmidt cameras have very strongly curved focal planes, thus requiring that the film, plate, or other detector be correspondingly curved.
The Mersenne-Schmidt camera consists of a concave paraboloidal primary mirror, a convex spherical secondary mirror, and a concave spherical tertiary mirror.
Schmidt - The man and his Camera - By Mark Christensen, Ph.D. (1259 words)
Bernhard Schmidt was born at the Estonian island of Nargen in 1879 of a Swedish mother and a German father.
Schmidt's solution to this problem was to introduce a thin lens, or plate, at the center of curvature of the mirror, that is, where the stop is shown in Figure 3.
Herr Schmidt built his first mirror-corrector telescopic camera in 1930, using a 17.3 inch mirror and a 14.2 inch corrector to achieve a focal ratio of f/1.7, producing a telescope of unheard of 'speed'.
  More results at FactBites »

 
 

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