History

    Rounded diaphragm

    The polygonal shape of a conventional iris dia phragm causes out-of-focus light points to appear polygonal. A rounded diaphragm is designed to pro duce rounded out-of-focus light points when opened to near maximum aperture. This creates attractive bokeh effects in many situations, such as when pho tographing a subject against an out-of-focus surface of water from which light is being reflected.