1. Field of the Invention
The present invention relates to an image pickup apparatus, such as a digital camera and a digital video camera.
2. Description of the Related Art
Japanese Patent Laid-Open No. (“JP”) 2003-295047 proposes a hybrid focus detection unit for moving a focus lens to a position near an on-focus position using an autofocus unit of a phase difference detection method (“phase difference AF”), and then for precisely moving the focus lens to the on-focus position using an autofocus unit of a contrast detection method (“contrast AF”). JP 2009-003122 realizes a phase difference detection function by providing an image pickup device with a focus detection pixel.
However, the contrast AF has a problem in that a high contrast background in a focus detection region increases a contrast and causes an erroneous detection of this contrast change (which will be referred to as a “false peak” hereinafter) as an on-focus position. In addition, a noise ratio at the image pickup time increases as the ISO sensitivity increases, and the false peak is detected due to the noises. Hence, there is a demand for improved contrast AF accuracy or ultimately the hybrid AF accuracy.