A dual lens optical system includes a first optical system redirecting an optical axis of light representing an image of an object by 90.degree. to form an image on a image sensor, and a second optical system having a movable reflection member configured to be selectively positioned on the part of the redirected optical axis of the optical axis of light passing through the first optical system, and redirecting the light representing the image of the object by 90.degree. using the movable reflection member to form an image on the image sensor, wherein the first optical system and the second optical system share lenses and the image sensor located after the movable reflection member along an optical path.