Ikelite 5506.5 Underwater Housing Port SLR Flat PortFlat ports are recommended for standard, macro and telephoto lenses. Due to refraction, flat ports reduce the angle of coverage of a lens and magnify the image. This makes the flat port ideal when using standard, macro or zoom lenses to shoot small subjects. Our focus ports feature built in gearing for lenses whose focus collar extends beyond the housing focus. Note that if a port is long enough to accommodate the full length of a 1: 1 macro lens, the