In a camera system of this invention, a light beam coming from a photographing lens is reflected by a quick return mirror in the widthwise direction of a body unit, and is reflected by a second mirror via a half mirror and screen in the upward direction of the body unit except for some light beam components. The light beam reflected by the second mirror is reflected by a third mirror in a direction opposite to that of the light beam reflected by the quick return mirror, and is also reflected by a fourth mirror toward an eyepiece side in the back side of the body unit. Some light beam components reflected by the half mirror are fetched by an AF sensor unit to detect the focal point position of the photographing lens.