The term fisheye, when related to lens design, was coined in 1906 by American physicist Robert W. Wood based on how a fish would see an ultra-wide hemispherical view from beneath the water (aka “Snell’s window.”) Yes, this is the same Robert W. Wood and definer of the “Wood Effect” in infrared photography.
Fisheye lenses were first used in meteorology during the 1920s for use to study cloud formation also giving them the name “whole-sky lenses.”
A fisheye lens is an ultra wide-angle lens that produces a wide panoramic or hemispherical image. Fisheye lenses achieve extremely wide angles of view by forgoing producing images that have straight lines of perspective, opting instead for an equisolid angle—think disco mirrorball effect—which gives images a characteristic non-rectilinear appearance. The angle-of-view of a fisheye lens is usually between 100 and 180 degrees, with (full-frame) focal lengths ranging from 8-10mm for circular images, and 15–16mm for more rectilinear images
I shot the above image with a Voigtlander Super-Wide Heliar 15mm f/4.5 Aspherical manual focus lens. This lens has a 110 degree angle-of-view and is ideal for landscape photography as well as tight interiors. This first generation lens (borrowed from Mark Toal) has a standard Leica L-mount (screw mount) that was attached to a Lumix GX1 using a Vello L to Micro Four-thirds adapter. Exposure was 1/1600 sec at f/16 and ISO 200.