The GV-1 is the optical viewfinder specially for GR, GR DIGITAL III / GR DIGITAL II / GR DIGITAL. You can attach the external viewfinder in the hot shoe that is located above the lens, which will not show vignetting caused by the lens barrel. It has the two frames that are equivalent to 28 mm and 21 mm (on 35 mm film cameras). The 21 mm frame will be useful when the wide conversion lens is attached. Field of view is approx. 90%. Includes case.