focus [of an earthquake] definition, focus [of an earthquake] meaning | English dictionary




      n   pl   , -cuses, -ci  
1    a point of convergence of light or other electromagnetic radiation, particles, sound waves, etc., or a point from which they appear to diverge  
2       another name for       focal point       1       focal length  
3      (Optics)   the state of an optical image when it is distinct and clearly defined or the state of an instrument producing this image  
the picture is in focus, the telescope is out of focus     
4    a point upon which attention, activity, etc., is directed or concentrated  
5      (Geometry)   a fixed reference point on the concave side of a conic section, used when defining its eccentricity  
6    the point beneath the earth's surface at which an earthquake or underground nuclear explosion originates  
   Compare       epicentre  
7      (Pathol)   the main site of an infection or a localized region of diseased tissue  
      vb   , -cuses, -cusing, -cused, -cusses, -cussing, -cussed  
8    to bring or come to a focus or into focus  
9    tr; often foll by: on   to fix attention (on); concentrate  
     (C17: via New Latin from Latin: hearth, fireplace)  
  focusable      adj  
  focuser      n  

automatic focus  
a    a system in a camera which automatically adjusts the lens so that the object being photographed is in focus, often one using infrared light to estimate the distance of the object from the camera  
b    (as modifier)  
automatic-focus lens        (Abbrev.)    AF     (Also called)    autofocus  
depth of focus  
      n   the amount by which the distance between the camera lens and the film can be altered without the resulting image appearing blurred  
   Compare       depth of field  
focus group  
      n   a group of people brought together to give their opinions on a particular issue or product, often for the purpose of market research  
focus puller  
      n     (Films)   the member of a camera crew who adjusts the focus of the lens as the camera is tracked in or out  
principal focus  
      n      another name for       focal point  
soft-focus lens  
      n     (Photog)   a lens designed to produce an image that is uniformly very slightly out of focus: typically used for portrait work  
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"Collins English Dictionary 5th Edition first published in 2000 © HarperCollins Publishers 1979, 1986, 1991, 1994, 1998, 2000 and Collins A-Z Thesaurus 1st edition first published in 1995 © HarperCollins Publishers 1995"