The resolving power of photographic lenses vary depending on the photographic lens model; however, in many photographic lenses, the resolving power is most enhanced when the diaphragm is slightly stopped down from full-open aperture. As shown in FIG. 5(A), the MTF generally increases as the opening of the diaphragm is reduced. However, although the MTF increases as the opening of the diaphragm is reduced, diffraction also occurs due to the influence of the diaphragm, so that stopping down the diaphragm more than a certain amount causes a decrease in the MTF. In addition, MTF varies according to the spatial frequency of an object, and the higher the spatial frequency of an object, the lower the MTF is (FIG. 5(B)). Taking the LPF effect into account, the LPF effect does not have to be made strong in the lens which is low in MTF at high frequency. For instance, in the case where the pixel pitch of the image sensor 17 is 6 μm, when a photographic lens with 80 percent of MTF at a spatial frequency of 170 lp/mm corresponding to the resolution limit of the image sensor 17 and a photographic lens with 20 percent of the same MTF are compared with each other, the LPF effect can be weakened in the photographic lens with 20 percent MTF because the contrast drops to 20 percent at a spatial frequency close to the pixel pitch, whereas the LPF effect needs to be made sufficiently strong in the photographic lens with 80 percent MTF because the contrast is sufficient at a spatial frequency close to the pixel pitch.