Patent ID: 9591205
Date: 2017-03-07
CPC Classifications: H04N

Claim:
1. A focus control apparatus configured to control drive of a focus element movable in an image capturing system that photoelectrically converts, by an image sensor, an object image formed by an optical system, the apparatus comprising: a first focus detector configured to perform a phase difference focus detection to calculate, from a phase difference between paired image signals produced using an output from the image sensor, a defocus amount of the image capturing system; a second focus detector configured to produce, with the focus element being driven, a contrast evaluation value corresponding to a contrast of the object image using the output from the image sensor; a reliability acquirer configured to acquire a reliability of the phase difference focus detection on a basis of a coincidence degree of the paired image signals and a contrast of the paired image signals; and a controller configured (a) to control the drive of the focus element on a basis of a phase difference in-focus drive amount that is a drive amount of the focus element to bring the image capturing system into a phase difference in-focus state and that is calculated from the defocus amount and (b) to control the drive of the focus element to bring the image capturing system into a contrast in-focus state by using the contrast evaluation value, when the reliability is higher than a first reliability and the defocus amount is larger than a first defocus amount, a first drive amount that is smaller than the phase difference in-focus drive amount by a first non-drive amount; when the reliability is higher than the first reliability and the defocus amount is smaller than the first defocus amount, the phase difference in-focus drive amount; and when the reliability is lower than the first reliability and higher than a second reliability and the defocus amount is larger than a second defocus amount, a second drive amount that is smaller than the phase difference in-focus drive amount by a second non-drive amount, and the controller is configured to drive the focus element, (a) when the reliability is lower than the first reliability and higher than the second reliability and the defocus amount is smaller than the second defocus amount and (b) when the reliability is lower than the second reliability, by using the contrast evaluation value.