The fisheye camera lens was created to show how a fish can have an ultra-wide hemispherical view underwater. Its first practical application didn't come until 1920 when meteorologists observed cloud formations in the sky. At that time, they were called "all-sky lenses." They are also used in aviation, astronomy, and of course, skateboarding videos, where most people encounter fisheye camera lens in simple peepholes. The photographic use of fisheye camera lens didn't start until the 1960s, when fisheye camera lens began to be mass-produced.
It's simple; the more the lens shape resembles a dome, the more light it can gather from different directions and "see" effectively. These lenses are spherical simply because they have to be spherical. Think about the eyes of predators and prey. Many fish have large, wide eyes on both sides of their heads, so they can see in all directions to avoid anything trying to eat them. In contrast, raptors have small eyes in front of their heads, so they can focus on a target with laser-like precision.
Think of a fisheye lens as a wide-angle lens and a zoom lens combined. If you want to see the entire scene and take it all in, you want to see like a fish; if you want to zoom in on a specific detail, you need to target it like a raptor with its laser. The focal length of a lens is measured in millimeters (mm), and any number below 24mm falls into the category of an ultra-wide-angle lens.
If you enjoy the look of an ultra-wide-angle lens, then they can truly be used for any subject. More specifically, fisheye lenses are excellent travel lenses because they can capture incredibly wide landscape images and can focus at a short distance while still allowing you to fill the frame with detail. They are also typically "fast" lenses, meaning they have a large aperture and can gather a lot of light. This makes them ideal for indoor photography in places like museums and churches.
Of course, if you enjoy extreme sports like deep-sea diving, skateboarding, or surfing, then a fisheye lens is a must-have tool for capturing close-up and personal action. Taking images of the entire night sky is like fisheye lenses taking a stroll in the park; the ultra-wide angle it can capture means you can take photos of the entire galaxy and, with some lenses, the entire night sky from horizon to horizon. Whether you are an experienced landscape photographer or an extreme sports enthusiast, a pro or a beginner, a fisheye lens may be just the creative choice you're looking for.