Ikelite SLR Focus Flat Port 5.5-6.5The Ikelite dome is injection molded specifically for underwater photography, and represents the finest optics in the industry. Recommended for wide angle lenses from 17mm to 28mm, and short zoom lenses Zoom lenses require a +4 diopter close up lens available from camera stores. Wide angle lenses will focus at 12" and do not require the addition of any close up lens when used in a dome port.