fisheye lens

noun Photography.

1. a hemispherical plano-convex lens for photographing in a full 180° in all directions in front of the camera, creating a circular image having an increasing amount of distortion from the center to the periphery.

noun

1. photog a lens of small focal length, having a highly curved protruding front element, that covers an angle of view of almost 180°. It yields a circular image having considerable linear distortion