An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

   Homepage   
   


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Number of Results: 1 Search : Nasmyth
Nasmyth focus
  کانون ِ نسمیت   
kânun-e Nasmyth (#)

Fr.: foyer Nasmyth   

In an altazimuth-mounted telescope, a focal point to one side of the tube, created by placing a third deflecting mirror in the optical path. This extra mirror directs the beam along the altitude axis, and through a hole in the supporting trunnions. Nasmyth focus has the advantage of remaining at a fixed position relative to the telescope wherever the instrument is pointed. Moreover, bulky or heavy instruments can be mounted there on a permanent platform, which rotates only in azimuth.

Named after the inventor James Nasmyth (1808-1890), who first used it in the 19-th century.