Sea & Sea M52 Wide-Angle Conversion Lens For Olympus PT Waterproof Cases The Sea & Sea M52 Wide-Angle Conversion Lens For Olympus PT Waterproof Cases is a wide-angle lens with an M52 screw mount designed for certain Olympus PT-series waterproof cases. It enables you to get closer to your subject while still fitting everything in-frame, thus minimizing distortion and improving image clarity and quality. The lens is constructed from a corrosion-resistant aluminum alloy with an anodized finish. It changes the camera"s focal length from 28mm to 18mm (35mm film equivalent), provides 0.65x magnification, and offers 85 and 106.5 angles of view underwater and on land, respectively. A true amphibian of a lens, it is usable both on land and underwater, and can be attached and removed beneath the surface, as well. It boasts a depth rating of 200" (60 m). When used on land, slight vignetting (dimming) may occur in the 4 corners of the image. Zoom in slightly to telephoto in order to eliminate this effect. Additionally, a shadow may appear in the image if the built-in flash is used while the lens is mounted. It is highly recommended that an external strobe be used to improve lighting quality. The lens is compatible with the Olympus PT-045, PT-047, PT-048, and PT-051 waterproof cases.