Patent ID: 7791667

Claim:
A focus detection apparatus configured to detect a focusing state of an image-pickup lens based on a phase difference in a plurality of images provided by splitting a luminous flux from the image-pickup lens, comprising: a field lens configured to have one optical axis and to split the luminous flux from the image-pickup lens, the field lens being decentered from an optical axis of the image-pickup lens; and a light-receiving element configured to include a plurality of focus detection areas for photoelectrically converting a plurality of paired images formed of the luminous flux passed through the field lens, wherein the light-receiving element includes: at least a first focus detection area and a second focus detection area which detect a phase difference in a first direction; and a third focus detection area and a fourth focus detection area which detect a phase difference in a second direction different from the first direction, and wherein the first focus detection area and the third focus detection area intersect with each other at a position on a first side with respect to a center of the first focus detection area, and the second focus detection area and the fourth focus detection area intersect with each other at a position on a second side opposite to the first side with respect to a center of the second focus detection area.