A fisheye lens is a special type of lens that is popular among DSLR enthusiasts that takes extremely wide angle pictures. Originally developed for use in meteorology, fisheye lenses allowed scientists to take wider pictures of the sky so they could capture entire cloud formations. For this use, fisheye lenses were called “whole sky lenses.” But the effect of the fisheye lens has gained popularity in other uses as well, from capturing long run ups and action shots for skateboarding and snowboarding videos to creating artistic effects for still photography.

If you’ve never seen a fisheye lens on a camera before, then you’re probably most familiar with the fisheye effect in the form of a peephole. Just like a peephole on a door lets you see a wider viewing angle in the hallway, a fisheye lens on a camera lets you capture more vertical or horizontal area in your picture without moving the camera.

Circular vs. Full-frame Lenses

Because fisheye lenses capture such a wide focal length, a certain amount of barrel distortion is inevitable. In this way, a fisheye lens differs from a panoramic photo. Photos taken with a fisheye lens will appear to bulge forward in the center, as if they were superimposed on a hemisphere.

For fisheye lens that have a 180 degree viewing angle, the image looks like a circle, with blank space appearing in the edges. As such, this is called a circular fisheye lens. This was the original type of fisheye lens.

More popular today are full-frame fisheye lenses. These have a 180 degree diagonal viewing angle and leaves no black space in the frame. However, the barrel effect is more dramatic around the horizontal edges and there is less of a fisheye effect in the top and bottom.

Rectilinear Projection

The barrel distortion on a full-frame fisheye lens photo can be “smoothed out” per se using software that creates a rectilinear projection. This produces an image that is more similar to a panoramic photo, though there is some loss of detail around the edges.

Pros and Cons of Fisheye Lenses

There are no real pros or cons of a fisheye lens, though there are certain situations where the unique barrel distortion of a fisheye lens can be advantageous. For example, when shooting skateboard videos, a fisheye lens allows the camera to focus on the skateboard to emphasize the movement while still keeping the skater in the shot.

Buying a Fisheye Lens

Buying a fisheye lens for your digital SLR camera or SLR camera is similar to buying any other type of lens for your camera. It’s best to match the brand of your camera to the brand of the lens, though there are usually third-party lenses that fit Canon, Nikon, Kodak, etc. cameras. Pay attention to specifications such as lens size, zoom, sensors and, of course, price.

If you are interested in creating an artistic effect with your DSLR or digital video camcorder, a fisheye lens will give you that barrel distorted effect or allow you to emphasize the action captured in the center of the frame. Fisheye lenses are also useful for security purposes, whether you are using surveillance cameras or installing a peephole.