An extreme wide angle lens for use with film, video and stills cameras.
Fish eye lenses are known for their "bulged centre and curved edge" image, which is often used for special effect. It is also good for broad landscapes, and whole sky images although the edge distortion is still very much part of the image and cannot easily be corrected.
Image from www.visuallee.com/weblog/2001_09_01_archive.html
