What is a Fish-Eye Lens?
A fish-eye lens is a special type of ultra-wide angle lens. They are small, ultra-wide, and show a distorted, spherical view of the world, most evident in the curved, outer corners of the photo.
Fish-eye lenses happen to work very well underwater for a couple different reasons:
- They focus very closely
- There are few straight lines underwater
- Using a very wide lens allows to get very close to your subjects, giving your photograph more sharpness, and better colours when lit with a strobe.
Behind a dome port, fish-eye lenses perform better optically than regular wide-angle lenses.
The term fish-eye was coined in 1906 by American physicist and inventor Robert W. Wood based on how a fish would see an ultra wide hemispherical view from beneath the water (a phenomenon known as Snell's window). Their first practical use was in the 1920s for use in meteorology to study cloud formation giving them the name "whole-sky lenses". The angle of view of a fish-eye lens is usually between 100 and 180 degrees while the focal lengths depend on the film format they are designed for.