At least one exemplary embodiment is directed to an imaging apparatus which includes a rear-focus-type lens system configured to perform autofocusing on the basis of a video signal received from an image pickup device. The imaging apparatus can determine a distance from a subject on the basis of correlation information (cam locus) detailing a correlation between the position of a zoom lens and the focus position of a focus lens, with respect to infrared light and visible light, and selects or calculates and determines a cam locus to be used.