The Nikon 16mm f2.8 AIS Fisheye-Nikkor is, as you may have guessed, a fisheye lens. It records a 170 degree image from corner to corner with all the circular distortion you'd expect from a fisheye. But it's a full-frame fisheye, so it will produce an edge-to-edge image that takes full advantage of your sensor's resolution. In excellent condition, with very minor cosmetic wear; glass is free of haze and fungus, with only minor dust and a few vanishingly small front element cleaning marks which won't affect imaging.