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The diopter is an aperture sight component used to assist the aiming of devices, mainly firearms, airguns, and crossbows. It is found in particular as a rear sight element on rifles. To obtain a usable sighting line the diopter has to have a complementing front sight element. Diopter and globe sighting lines are commonly used in ISSF match rifle shooting events. ==Diopter rear sight== The diopter is in principle a height and sideways (elevation and windage) adjustable occluder with a small hole (aperture), and is placed close in front of the shooter's aiming eye. Through this small hole the shooter can view the front sight component(s) and the intended target. The typical occluder used in target shooting diopters is a disc of about 2.5 cm (1 in) in diameter with a small hole in the middle. The small diopter viewing opening ensures the shooter's eye is very precisely and consistently centered behind the diopter sight. The diopter sight is easy to use and usually allows for very accurate aiming, because a relative long sighting line can be used. A long sighting line helps to reduce eventual angle errors and will, in case the sight has an incremental adjustment mechanism, adjust in smaller increments when compared to a further identical shorter sighting line. High end target shooting diopters normally accept accessories like rubber eye shields, adjustable diopter aperture (typically between to ) and optical filter systems for the aiming eye and semi-transparent occluders for the non-aiming eye to ensure optimal sighting conditions for match shooters. Typical modern target shooting diopters offer windage and elevation corrections in (≈ 0.069 MOA) to (≈ 0.172 MOA) increments at . Some ISSF (Olympic) shooting events require this precision level for sighting lines, since the score of the top competitors last 10 shots is expressed in 0.1s of scoring ring points. 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「Diopter sight」の詳細全文を読む スポンサード リンク
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