If you can't afford a fisheye lens, there is an alternative in the form of image-editing software.
There are quite a few fisheye lenses available, but they are not usually found at bargain-basement prices. Fortunately, there are a few alternative ways to get the same look. As is often the case in this era of digital technology, some image-editing packages such as Adobe Photoshop and Photoshop Elements can be used to introduce the signature distortion.
The easiest way to mimic the appearance of an image shot through a fisheye lens is to use the Spherize filter, but this only works on a central circular portion of the picture. Careful selection is required to remove the surrounding undistorted section of the image so that the circular fisheye look is created.
Another more satisfactory approach uses Photoshop’s Warp transformation. This is much more flexible than the Spherize filter and allows the photographer to stretch and distort the image to taste and still produce a rectangular picture with the original aspect ratio.
Using Photoshop CS4, you can accomplish the fish eye look. If you can't come across a fish eye lens, which can cost you a pretty penny. There is an alternative with pretty fantastic results.