A fisheye lens is an ultra-wide angle lens for a DSLR camera that captures a hemispherical (round) image. This creates visual distortion that is obvious and often used in creative photography. The result is an image that looks as if the edges of the photo are wrapped around a spherical shape, with curved lines and a changing context of everything on the outer edge of the photo.
What is a fisheye lens?
The angle that a fisheye lens can capture is approximately 180 degrees, which is why it is considered an ultra-wide angle lens. A wide angle lens can capture an image that is approximately 100 degrees wide. This creates an image that looks as if it was taken through a peephole, such as those often seen in doorways.
Fisheye lenses also have a distinctive look because the outer glass of the lens has a much more pronounced curve than a wide-angle lens. This curve allows the lens to capture a greater range of light and take photos that are wider than your average wide-angle lens.
All DSLR lenses, except fisheye lenses, are called rectilinear lenses. This is because light travels in a straight line through the lens to the image sensor. This creates the straight lines you see in most photographs.
