1. An electronic imaging apparatus comprises an imaging optical system, and an imaging device which converts an object image obtained via the imaging system to an electric signal. All of medium of optical elements which is disposed in a space between a most object side of the imaging system and the imaging device is constituted with optically isotropic medium. A diameter of a point image at the open F value of the imaging system is bigger than a pitch of a picture element. The following condition is satisfied; F>1.4a(0