Focus control apparatus, image sensor, program and storage medium

Abstract

A digital camera has distance measurement zone setting means ( 12 ) for dividing distance to a subject into a plurality of distance measurement zones; distance measurement zone selection means ( 13 ) for selecting a distance measurement zone to be scanned; an autofocus evaluation calculation circuit ( 14 ) for acquiring an AF evaluation value by scanning the selected distance measurement zone; zone-update determination means ( 15 ) for determining, through use of the AF evaluation value, whether or not to update a distance measurement zone to be scanned; and in-focus position decision means ( 16 ) for appropriately updating the scanned distance measurement zone based upon the determination as to whether to update the distance measurement zone, and deciding an in-focus position based upon acquisition of AF evaluation value. A focusing lens ( 2 ) is driven to the in-focus position by a focusing-lens drive circuit ( 17 ).

1 . A focus control apparatus for detecting in-focus position of a focusing optical unit by performing scanning of moving the focusing optical unit in accordance with a predetermined range, comprising:
 a scanning area selection unit adapted to divide a movable range of the focusing optical unit into a plurality of scanning areas and select a scanning area to be scanned; and   an in-focus state acquisition unit adapted to acquire the in-focus state of the focusing optical unit by scanning the selected scanning area;   wherein the scanning area selection unit changes number of scanning areas to be divided is changed in accordance with the focal length.   
   
   
       2 . The apparatus according to  claim 1 , wherein number of scanning areas to be divided is changed in accordance with focal length at time photography. 
   
   
       3 . The apparatus according to  claim 2 , wherein the greater the focal length at the time of photography, the larger the number of scanning areas to be divided is made. 
   
   
       4 . The apparatus according to  claim 1 , wherein the number of scanning areas to be divided is changed also in accordance with f-stop value at time of photography. 
   
   
       5 . The apparatus according to  claim 4 , wherein the more an aperture is stopped down, the smaller number of scanning areas to be divided is made. 
   
   
       6 . An image sensor having an in-focus control apparatus defined in  claim 1 . 
   
   
       7 . An image sensing apparatus that performs scanning in a scanning area by moving a focusing optical unit so as to determine in-focus to an object, comprising:
 a driving unit adapted to output driving signal to the focusing optical unit; and   a control unit adapted to divide a movable range of the focusing optical unit into plural scanning areas and changes a method of dividing the movable range of the focusing optical unit,   wherein the number of scanning areas to be divided is changed in accordance with focal length.   
   
   
       8 . The apparatus according to  claim 7 , wherein the method of dividing the movable range of the focusing optical unit is changed in accordance with conditions of photography. 
   
   
       9 . The apparatus according to  claim 7 , wherein number of the scanning areas is changed in accordance with focal length at time of photography. 
   
   
       10 . The apparatus according to  claim 9 , wherein the greater the focal length at the time of photography, the larger the number of the scanning areas is made. 
   
   
       11 . The apparatus according to  claim 7 , wherein the number of scanning areas is changed also in accordance with f-stop value at time of photography. 
   
   
       12 . The apparatus according to  claim 11 , wherein the more an aperture is stopped down, the smaller number of divided areas is made. 
   
   
       13 . The apparatus according to  claim 7 , wherein the number of scanning areas is changed in accordance with conditions of photography. 
   
   
       14 . The apparatus according to  claim 7 , wherein the number of scanning areas is changed in accordance with luminance level at time of photography. 
   
   
       15 . The apparatus according to  claim 7 , wherein the number of scanning areas is set in accordance with mode of photography. 
   
   
       16 . The apparatus according to  claim 7 , wherein the number of scanning areas is set giving priority to short distances in a flash photography mode.