Sin Tax Bill Essay

634 WordsJan 5, 20133 Pages
------------------------------------------------- Focal length "Rear focal distance" redirects here. For lens to film distance in a camera, see Flange focal distance. The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a shorter focal length has greater optical power than one with a long focal length; that is, it bends the rays more strongly, bringing them to a focus in a shorter distance. In most photography and all telescopy, where the subject is essentially infinitely far away, longer focal length (lower optical power) leads to higher magnificationand a narrower angle of view; conversely, shorter focal length or higher optical power is associated with a wider angle of view. On the other hand, in applications such as microscopy in which magnification is achieved by bringing the object close to the lens, a shorter focal length (higher optical power) leads to higher magnification because the subject can be brought closer to the center of projection. ------------------------------------------------- Focal point Focal point may refer to: * Focus (optics), the point at which initially collimated rays of light meet after passing through a convex lens, or reflecting from a concave mirror * In Fine art, a Focal Point focuses specifically on a point of interest which makes a canvas unique. (e.g. Girl with a Pearl Earring by Johannes Vermeer) * In mathematics: * Focus (geometry), a special point used in describing conic sections * Focal point is a Critical point of a distance function * In an antenna (electronics): * The driven element, directly connected to the transmission line or source * The passive radiator, a conductive element which is not

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