An image of a subject is taken by a solid image taking device including a
first image taking element having a plurality of pixels and a second
image taking element having a plurality of pixels smaller than those of
the first image taking element. First and second evaluations on contrast
obtained by integrating high-frequency components of first and second
image signals representing an image of the subject taken by the first and
second image taking elements are calculated. The focus is adjusted on the
basis of the first and second evaluations on contrast so that the subject
is imaged on the solid image taking device.