These lenses are ultra-wide and uncorrected
Aptly named for their extreme coverage (180 degrees for the Nikon versions), fisheye lenses trade straight-line correction for a wraparound view. These were in vogue in the 1970s, and there used to be many different designs, with the basic distinction being between circular (projecting a circular image on the sensor surrounded by black) and the self-explanatory full-frame. The extreme imagery possible made them a novelty initially, but the overwhelming barrel distortion can make anything more than occasional use repetitive and over-the-top. Nikon produces what is essentially the same lens in FX and DX format – the Nikon AF 16mm f/2.8 Fisheye and the Nikon AF DX 10.5mm f/2.8G Fisheye.