Patent ID: 8823838

Claim:
An image pickup system comprising: an image pickup apparatus in which, photoelectric conversion cells which convert an optical image which has been formed by a taking lens to an electric signal, are arranged two-dimensionally, wherein at least some of the photoelectric conversion cells are arranged to output a signal for detecting an amount of defocus, and the photoelectric conversion cells which output the signal for detecting the amount of defocus constitute at least two photoelectric conversion cell groups, each receiving a light beam from a pupil area having a different area, and each photoelectric conversion cell group has a plurality of photoelectric conversion cell columns, and the image pickup system further comprising: a calculating section which has an auto focus (AF) mode which generates a defocus signal by comparing mutually the signals for detecting the amount of defocus, which have been output from the two photoelectric conversion cell groups; and a correction section which corrects the signal for detecting the amount of defocus, from information related to distortion of the taking lens, wherein the taking lens satisfies the following conditional expression: 0.05≦|(1 −Yim /( f ·tan(ω im )))|≦0.35 where f denotes a focal length of the taking lens, Yim denotes an arbitrary image height in a range of 0.4 to 0.8 when a distance from a center in an effective image pickup surface of an electronic image pickup element up to the farthest point is let to be 1, and ωim denotes an angle with respect to an optical axis in an object-point direction corresponding to image points connecting from the center on the effective image pickup surface of the electronic image pickup element up to a position of Yim.