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A finderscope is an aiming device used in astronomy, typically a small auxiliary telescope mounted on the main astronomical telescope along the same line of sight. The finderscope usually has a smaller magnification than the main telescope, providing a much larger field of view, useful for manually aiming (also called "slewing") a telescope and locating a desired astronomical object. Some finderscopes have crosshairs to aid in accurately pointing the telescope system at a target. ==Function and Design== Finderscopes contain mechanisms to properly align them with the main telescope's line of sight. Accomplishing this alignment varies based on the design of the finderscope and its mount: usually on amateur telescopes it is done by three or six adjustment screws. Finderscopes usually come with a designation of the form A×B, where A is the magnification and B is the aperture of the finderscope's objective lens in millimeters; for example, a 6×30 finderscope means a finderscope with a 30 mm objective and a magnification of 6×. This designation is in the same format used by most binoculars.〔(【引用サイトリンク】url=http://www.meade.com/support/selbinoc.html )〕 A 6×30 finderscope is typically considered the minimum useful size for a magnifying finderscope on an amateur telescope, and an 8×50 or larger finderscope is preferred for more accurate aiming.〔"The Backyard Astronomer's Guide", by Terence Dickinson and Alan Dyer.〕 Most finderscopes have one of three viewing orientations: 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「finderscope」の詳細全文を読む スポンサード リンク
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