Fisheye Lenses: 5 Fast Facts

Fact #1. Two major factors define a fisheye lens. The first is the wide field of view. That's what makes them attractive. You can see much more than without them. The second is the intense barrel distortion. That's what makes them distinctive. It's also what separates them from other wide angle lenses. This distortion produces an even curve around the edges.
Fact #2. You probably know them for a couple reasons. If you ever find yourself watching music videos from the 1990s, you'll likely spot one. Especially if you find anything from Hype Williams' videography. He lent his signature style to everyone from Busta Rhymes to Missy Elliott to No Doubt. The other reason are skate videos. That's the same time period when the X-Games were big. To this day, many skaters overuse the lens.
Fact #3. In recent years they've had a resurgence. This is in large part thanks to the popularity of the GoPro camera. Other action cameras have followed suit. They all need nearly all-inclusive fields of view. Otherwise you would miss out on the action. Plus there's the legacy of the X-Games. Since these action cameras are largely waterproof, they even live up to the piscine name.
Fact #4. The distinguishing factor is that they have an overtly convex front lens element. Light hits it from a far greater number of angles than a rectilinear lens captures. It then funnels through a system of additional elements that focus the image. The result is a sharp, evenly distorted image.
Fact #5. Fish don't actually have as short of a memory as you were lead to believe. But these lenses aren't a bad representation of how they actually see. Recent studies have found that many fish have memories that last up to five months. Hopefully the camera you're attaching one of these lenses to can still beat that.