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eyepiece
eyepiece A lens or combination of lenses used to magnify the image formed by a telescope; also known as an ocular. The simplest form of eyepiece is a single converging lens of short focal length, but this has severe aberrations except at the very centre of its field of view. In practice, therefore, eyepieces usually have at least two elements. A field lens, facing the objective or mirror, gathers light over a wider field than a single lens, while the eye lens, through which the observer looks, provides the magnification. This combination gives a good field of view while keeping aberrations under control. A field stop (a diaphragm located so that it is in focus as seen through the eye lens) provides a hard edge to the field of view. Many additional elements can be included to improve performance. Popular designs include the Erfle, Huygenian, Kellner, monocentric, Nagler, orthoscopic, Plössl, and Ramsden eyepieces.
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"eyepiece." A Dictionary of Astronomy. 1997. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "eyepiece." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O80-eyepiece.html "eyepiece." A Dictionary of Astronomy. 1997. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-eyepiece.html |
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eyepiece
eyepiece (ocular) An eye lens, a fixed diaphragm with cross-wires, and a field lens, all contained in a short tube which is inserted into the top of a microscope. The internal construction of the eyepiece may vary depending on whether the focal plane lies above (Huygenian or negative eyepiece) or below (Ramsden or positive eyepiece) the field lens. Most eyepieces are either 5× or 10× magnification.
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AILSA ALLABY and MICHAEL ALLABY. "eyepiece." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. AILSA ALLABY and MICHAEL ALLABY. "eyepiece." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O13-eyepiece.html AILSA ALLABY and MICHAEL ALLABY. "eyepiece." A Dictionary of Earth Sciences. 1999. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-eyepiece.html |
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eyepiece
eye·piece / ˈīˌpēs/ • n. the lens or group of lenses that is closest to the eye in a microscope, telescope, or other optical instrument. |
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Cite this article
"eyepiece." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "eyepiece." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O999-eyepiece.html "eyepiece." The Oxford Pocket Dictionary of Current English. 2009. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-eyepiece.html |
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eyepiece
eyepiece (ocular) The lens or system of lenses in an optical instrument that is nearest to the eye. It usually produces a magnified image of the previous image formed by the instrument.
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Cite this article
"eyepiece." A Dictionary of Biology. 2004. Encyclopedia.com. 31 May. 2012 <http://www.encyclopedia.com>. "eyepiece." A Dictionary of Biology. 2004. Encyclopedia.com. (May 31, 2012). http://www.encyclopedia.com/doc/1O6-eyepiece.html "eyepiece." A Dictionary of Biology. 2004. Retrieved May 31, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-eyepiece.html |
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