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: 10 Search : focus
apofocus
  اپاکانون   
apâkânun

Fr.: apocentre   

The point on an elliptic orbit at the greatest distance from the principal focus. Also knwon as → apocenter.

From → apo- "away from, off," + → focus.

From apâ-, → apo-, + kânunfocus.

Cassegrain focus
  کانون ِ کسگرن   
kânun-e Cassegrain (#)

Fr.: foyer Cassegrain   

The main focus in → Cassegrain telescope.

Cassegrain telescope; → focus.

coudé focus
  کانون ِ آرنج‌وار   
kânun-e ârenjvâr, ~ kudé

Fr.: foyer coudé   

An optical system in which the beam of light from the primary mirror is reflected down through the instrument's polar axis by a path bent like an elbow. Since the focus remains fixed with respect to the earth, light can be analyzed with permanently installed instruments. In addition long focal lengths allow higher spectral dispersions.

From Fr. coudé "elbowed," from coude "elbow," L. cubitus; → focus.

Kânun, → focus; ârenj "elbow," variants âranj, âran, Mid.Pers. âranj, O.Pers. "cubit," Av. arəθnâ- "elbow," Skt. aratni- "elbow," Iranian stem aratan-, araθn-, borrowed from Iranian into General Slavic as aršin "ell" + -vâr suffix denoting "in the manner of; resembling."

defocus
  واکانونیدن   
vâkânunidan

Fr.: défocaliser   

To cause to deviate from accurate focus.

vâ- + → focus.

focus
  ۱) کانون؛ ۲) کانونیدن   
1) kânun; 2) kânunidan

Fr.: 1) foyer; 2) focaliser   

1) (n.) A point where parallel light rays from an object are gathered together by a lens or a concave mirror. It is the place where the clearest image of a distant object forms. Also called focal point. See also → focal distance.
2) (v.) To adjust the eyepiece or objective of a telescope so that the image is clearly seen by the observer.

From L. focus "hearth, fireplace," of unknown origin,

Kânun "hearth, fireplace."

focused
  کانونیده   
kânunidé

Fr.: focalisé   

Of an optical system, being in focus or brought into focus; adjusted to produce a clear image.

Past participle of → focus.

focusing
  کانونش   
kânuneš

Fr.: focalisation   

The act of bringing into focus.

Noun of → focus.

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.

Newtonian focus
  کانون ِ نیوتن، ~ نیوتنی   
kânun-e Newton, ~ Newtoni

Fr.: foyer de Newton   

The focus obtained by diverting the converging light beam of a reflecting telescope to the side of the tube.

Newtonian; → focus.

prime focus
  کانون ِ نخستی   
kânun-e naxosti

Fr.: foyer primaire   

The focal point of a large primary reflecting mirror. This focus actually falls at a point just within the upper structure of the telescope and provides a large field of view.

primary; → focus.