What is the difference between a fisheye lens and an ultra-wide-angle lens?

Whether it is a straight vertical or horizontal line, the fisheye lens will bend it. The ultra-wide-angle lens can express straight lines as straight lines after optical correction. For fisheye lenses, straight lines can be bent to cause deformation, which is suitable for shooting that emphasizes certain special effects.

A fisheye lens is a lens with a focal length of 16mm or shorter and a viewing angle close to or equal to 180°. It is an extreme wide-angle lens with the highest viewing angle among many lenses. In order to achieve the maximum photographic angle of the lens, the front lens of this photographic lens is very short in diameter and protrudes parabolically towards the front of the lens, which is quite similar to the eye of a fish, hence the name "fisheye lens". The fisheye lens is a special type of ultra-wide-angle lens, and its viewing angle strives to reach or exceed the range that the human eye can see. Therefore, there is a big difference between the fisheye lens and the real world scenes in people's eyes, because the scenery we see in real life has regular and fixed shapes, and the picture effect produced by the fisheye lens goes beyond this category. . Many photographers like to use the exaggerated deformation of fish glasses to create a sense of perspective.

Among wide-angle lenses, ultra-wide-angle lenses are called lenses with a particularly wide viewing angle range (80-110 degrees). On a 35mm camera, it mostly refers to a 15-20mm lens. The ultra-wide-angle lens has a wide field of view and does not have strong distortion like the fisheye lens. It is a lens that can eliminate distortion very well.