IMAGE PHOTOGRAPHING DEVICE, DISTANCE COMPUTING METHOD FOR THE DEVICE, AND FOCUSED IMAGE ACQUIRING METHOD

An optical restriction using a telecentric optical system, a process amount restriction in which a deteriorated image reconstructing process is executed a plurality of number of times, and the like exist. An apparatus has: an observation image photographing unit 221 for obtaining a plurality of observation images by photographing a same object by a plurality of aperture patterns; a calculating unit 222 for calculating optical transfer characteristics according to a distance to the object; and a distance arithmetic operating unit 206 for calculating the distance to the object from the plurality of observation images and the optical transfer characteristics. The apparatus also has: the observation image photographing unit 221 for obtaining a plurality of observation images by photographing the same object by a plurality of aperture patterns; the calculating unit 222 for calculating the optical transfer characteristics according to the distance to the object; an optical transfer characteristics arithmetic operating unit 206 for calculating optical transfer characteristics which minimize a blur amount from the plurality of observation images and the optical transfer characteristics; and a blur reconstructing unit 207 for obtaining an in-focus image by reconstructing a blur of the image by using the optical transfer characteristics which minimize the blur amount.