Fisheye lenses are basically ultra wide angle. These very specific lenses are most often used in abstract photography, and allows you to capture the most panoramic view given by any other type of photography lens. These lenses use a particular type of “mapping” that purposely distort lines given a more convex appearance. As the name implies, fisheye lenses look just like actual fish eyes, giving a panoramic view of anywhere from 100-180 degrees.

Rokinon 8mm Ultra Wide Angle Fish Eye Lens