Patent ID: 6618560
Filing Date: 2003-09-09
Classification: G02B

Abstract:
A focus detection device for a camera having a photographing lens, comprising:a pupil dividing system that divides a pupil of the photographing lens into a pair of focus detection areas; an intensity distribution pattern forming system that receives light passed through said focus detection areas and forms a pair of intensity distribution patterns, a relative position thereof varying depending on a focusing condition of the photographing lens; a plurality of light receiving elements arranged in a direction where the pupil is divided; a focus detection area defining system that has a focus detection opening, said focus detection area defining system being arranged on or in a vicinity of a plane equivalent to a focal plane of the photographing lens, light passing through said pair of focus detection areas passing through said focus detection opening; a deflection prism arranged between said focus detection opening and said pupil dividing system, said deflection prism deflecting the light passed through said focus detection opening in a direction perpendicular to the pupil dividing direction and an optical axis of the photographing lens; and an optical element provided in a vicinity of said pupil dividing system, said optical element having an anamorphic refractive power, a refractive power in the pupil dividing direction being greater than a refractive power in a direction perpendicular to the pupil dividing direction.