US 7,321,725 B2
Light-amount control device for photographing
Shuzo Seo, Saitama (Japan); and Shinichi Kakiuchi, Saitama (Japan)
Assigned to PENTAX Corporation, Tokyo (Japan)
Filed on Nov. 04, 2004, as Appl. No. 10/980,284.
Claims priority of application No. P2003-382299 (JP), filed on Nov. 12, 2003.
Prior Publication US 2005/0100334 A1, May 12, 2005
Int. Cl. G03B 15/05 (2006.01); H04N 5/222 (2006.01)
U.S. Cl. 396—61  [396/164; 348/371] 6 Claims
OG exemplary drawing
 
1. A light-amount control device, comprising:
a plurality of lighting units, each of which emits light which illuminates a photographing area of a photographing optical system that comprises a zooming optical system;
a memory that stores peripheral light amount data, calculated based on a focal length of said photographing optical system and defining ratios of light emission intensities for said lighting units, to make an illuminance of an image plane of an object, having a flat surface perpendicular to an optical axis of said photographing optical system and having a constant reflecting light ratio, constant when said object is illuminated by said lighting units, said image plane being formed by light reflected from said surface of said object and entering said photographing optical system; and
a lighting unit controller that controls said lighting units so that the intensity of light at a wider illuminating angle to the optical axis of said photographing optical system becomes higher, based on said peripheral light amount data.