Patent ID: 7098955

Claim:
An optical apparatus, comprising: a photographic optical unit having a fixed focal length; a light amount adjusting unit disposed in an optical path of said photographic optical unit, said light amount adjusting unit varying an aperture to adjust an amount of light and changing an F-number by varying the aperture; an image pickup device for picking up an optical image formed by said photographic optical unit; a mode switching member for selecting a dynamic image taking mode and a static image taking mode; and a controller for controlling the variation in the aperture by said light amount adjusting unit, wherein said controller sets different values of the F-number of said light amount adjusting unit at the fixed focal length of said photographic optical unit in accordance with a state selected by said mode switching member, wherein, when said mode switching member selects the static image taking mode, said controller sets an F-number for a minimum aperture of said light amount adjusting unit in the static image taking mode to be smaller than an F-number for a minimum aperture of said light amount adjusting unit in the dynamic image taking mode at the fixed focal length of said photographic optical unit, and wherein said image pickup device comprises a plurality of light receiving pixels repeatedly arranged with a predetermined pitch, and a condition below is satisfied: 0.2< Fs min×λ/ P< 4.4 where P represents the pitch of said repeatedly arranged light receiving pixels, λ represents a reference wavelength for image taking of a light ray sensed by said image pickup device, and Fsmin represents the F-number for the minimum aperture of said light amount adjusting unit in the static image taking mode.