Patent ID: 7916194

Claim:
An image pickup apparatus comprising: an element-including optical system including an optical system having an optical axis (z axis) and two axes perpendicular to the z axis and to each (x axis and y axis) and an optical wavefront modulation element that modulates an optical transfer function wherein a phase of said optical wavefront modulation element is expressed as z = exp ⁢ { ⅈ × ( ∑ j = 1 ⁢ C j ⁢ x m ⁢ y n ) } where m and n are integers and j = [ ( m + n ) 2 + m + 3 ⁢ n ] 2 ,  x  ≤ 1 , and ⁢ ⁢  y  ≤ 1 are satisfied; a detector configured to pick up an object image that passes through said optical system and said optical wavefront modulation element; and a converter configured to generate an image signal with a smaller blur than that of a signal of a blurred object image output from said detector by performing a filtering process of the optical transfer function to improve a contrast, wherein a focal position of said element-including optical system is set by moving said element-including optical system to the focal position, the focal position corresponding to a predetermined object distance using a contrast of the object based on the image signal.