| US 7,526,192 B2 | ||
| Focus detection method and focus detection apparatus | ||
| Naoto Nakahara, Saitama (Japan) | ||
| Assigned to Hoya Corporation, Tokyo (Japan) | ||
| Filed on Oct. 07, 2005, as Appl. No. 11/245,045. | ||
| Claims priority of application No. 2004-295045 (JP), filed on Oct. 07, 2004. | ||
| Prior Publication US 2006/0078323 A1, Apr. 13, 2006 | ||
| Int. Cl. G03B 3/00 (2006.01); G03B 13/00 (2006.01) | ||
| U.S. Cl. 396—104 [396/127; 348/349; 348/353] | 13 Claims |
| 1. A focus detection method for detecting a focus state of an object image in accordance with a contrast of the object image
that is formed in a focus detection area, the focus detection method comprising:
capturing a plurality of object images while moving a focusing lens group of a photographing lens stepwise within a predetermined
range of movement of said focusing lens group;
determining contrast values of the plurality of object images in the focus detection area;
determining whether a contrast value of the contrast values of the plurality of object images is a peak contrast value, wherein
a particular contrast value is determined to be a peak contrast value when a first predetermined number of consecutive contrast
values preceding the particular contrast value increase in value and a second predetermined number of consecutive contrast
values succeeding the particular contrast value decrease in value, the determination being made when the focusing lens group
is moved stepwise in a predetermined direction; and
moving the focusing lens group to a position in which a maximum contrast value is determined when a peak contrast value is
not detected, the maximum contrast value being determined at one of at the closest focusing position and within a close vicinity
of the closest focusing position.
|