FOCUS DETECTION APPARATUS, IMAGE CAPTURING APPARATUS, AND FOCUS DETECTION METHOD

摘要

A focus detection apparatus detects a focus state of a subject using first and second pixel signals obtained by performing photoelectric conversion on subject light beams which have passed through different pupil regions of an imaging optical system. The focus state of a subject is detected from the first and second pixel signals. Further, each of the first pixel signals and second pixel signals are added by a predetermined addition number, and then the added first pixel signals and second pixel signals are relatively shifted. Thereafter, an evaluation value is calculated based on a signal obtained by adding the shifted first pixel signals and the second pixel signals and a defocus amount is detected from the evaluation value. The predetermined addition number is set in accordance with the focus state.

主权项

1. A focus detection apparatus that detects a focus state of a subject using first pixel signals and second pixel signals obtained by performing photoelectric conversion on subject light beams which have passed through different pupil regions of an imaging optical system for forming an optical image of the subject, the focus detection apparatus comprising:
a first detection unit configured to detect the focus state of the subject from the first pixel signals and second pixel signals; an addition unit configured to add each of the first pixel signals and second pixel signals by a predetermined addition number; a calculation unit configured to relatively shift the first pixel signals and second pixel signals that have undergone the addition by the addition unit, and calculate an evaluation value based on a contrast of a signal obtained by adding the first pixel signals and the second pixel signals after being shifted; and a second detection unit configured to detect a defocus amount from the evaluation value, wherein the addition unit sets the predetermined addition number in accordance with the focus state detected by the first detection unit.