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: 11 Search : focal
afocal
  اکانون، بی‌کانون   
akânun, bikânun (#)

Fr.: afocal   

Describing a lens or optical system with a convergent power of zero, whose object and image points stretch to infinity. Thus, → afocal system.

Afocal, from → a- + → focal.

Akânun, from a- negation prefix, → a- + kânun, → focus. Bikânun, from bi- negation prefix + kânun, → focus.

afocal system
  راژمان ِ اکانون   
râžmân-e akânun

Fr.: système afocal   

An optical system with object and image points at infinity.

afocal; → system.

effective focal length
  درازا‌ی ِ کانونی ِ ا ُسکرمند   
derâzâ-ye kânuni-ye oskarmand

Fr.: longueur focale effective   

The focal length of an imaging system, which consists of several lenses or mirrors.

effective; → focal length.

focal
  کانونی   
kânuni (#)

Fr.: focal   

Of or relating to a focus; placed at or measured from a focus.

focus + → -al.

focal distance
  دورای ِ کانونی   
durâ-ye kânuni

Fr.: distance focale   

same as → focal length.

focal; → distance.

focal length
  درازای ِ کانونی   
derâzâ-ye kânuni

Fr.: longueur focale   

The distance between the optical center of a lens, or the surface of a mirror, and its focus.

focal; → distance.

focal plane
  هامن ِ کانونی   
hâmon-e kânuni

Fr.: plan focal   

A plane at right angles to the principal axis of a lens or mirror on which the best image is formed.

focal; → plane.

focal point
  نقطه‌ی ِ کانونی   
noqte-ye kânuni

Fr.: point focal   

Same as → focus.

focal; → point.

focal ratio
  وابر ِ کانونی   
vâbar-e kânuni

Fr.: rapport focal   

The ratio of the → focal length of a reflecting surface or lens to its effective diameter, i.e. to its → aperture. The smaller the focal ratio, the smaller the image scale and the more luminous the image for a given aperture.

focal; → ratio.

focal reducer
  کاهنده‌ی ِ کانونی، باز‌هازنده‌ی ِ ~   
kâhande-ye kânuni, bâzhâzande-ye ~

Fr.: réducteur focal   

An optical component or system for changing the image scale of a telescope to achieve a better match between the → seeing disk and the → pixel size.

focal; → reducer.

nominal focal length
  درازای ِ کانونی ِ نامین   
derâzâ-ye kânuni-ye nâmin

Fr.: distance focale nominale   

An approximate value of the → focal length, used for the classification of lenses, mirrors, or cameras, as opposed to the measured one.

nominal; → focal; → length.