Abstract: A camera apparatus having means for setting an optical grating at a desired location in the viewfinder includes a viewfinder for observing a prospective image plane of an objective lens, a light dividing mirror for reflecting the light toward the viewfinder, and a scanning plate having a reflective optical grating thereon for scanning the image of an object on the prospective image plane. Light receiving circuitry is provided for receiving light reflected by the optical grating through the light dividing mirror, and for forming an electrical signal representing the focus adjusting state of the objective lens. Structure is provided for setting the optical grating in a desired position in the viewing field of the viewfinder.