A first scale component is stationarily mounted on a stationary lens component relative to which a rotatable lens component is supported. A pointer is supported from the rotatable lens component for angular displacement therewith and the first scale component includes first linear lens stop scale indicia thereon relative to which the pointer is registered and along which the pointer may swing. A second scale component including a second linear size compensation scale is provided and supported from the second scale component for back and forth shifting relative thereto for longitudinally shifting of the size adjustment scale generally along the path of swinging movement of the pointer. A third scale component including a third linear density value scale is supported from the first scale component for back and forth longitudinal shifting of the density scale transverse to the longitudinal extent of an adjacent portion of the size component scale.