Autofocus detector, autofocus detection method and autofocus detection program

摘要

PROBLEM TO BE SOLVED: To calculate a highly accurate defocus amount even when a plurality of subjects having different shooting distances coexist in a focus detection area. An automatic focus detection device includes a correlation calculation unit that performs a correlation calculation on an image signal sequence output from a sensor sequence, a reliability determination unit that determines the reliability of the correlation calculation result, and a determination that the reliability is present. Then, the defocus amount calculation unit that calculates the defocus amount based on the correlation calculation result determined to be reliable, and the start end side of the image signal string that has been subjected to the correlation calculation if it is determined to be unreliable. By comparing the reliability of the image signal and the reliability of the image signal on the terminal side, and excluding at least one of the image signals on the start side and the end side from the image signal sequence based on the comparison result, the image signal It is provided with a narrowing unit for narrowing down the columns, and the narrowing down unit narrows down the image signal trains and the correlation calculation unit performs correlation calculation on the range of the narrowed down image signal trains until it is determined to be reliable. [Selection diagram] Fig. 6