Circular Fisheye. The Sigma 8mm f/3.5 EX DG Fisheye provides the completely circular image with a 180º angle of view within a black surrounding frame (see Roger’s Take for example images). If you’re looking for an ultra-wide image that fills the image frame (this is called a rectilinear fisheye), this is not the lens for you.

Exaggerated Perspective. The Sigma can focus as close as 5.3 inches, providing some interesting close up effects, especially given its huge depth of field. It allows full time manual focus, but autofocuses quickly and accurately.

Specific Use. The Sigma 8mm gives interesting (bizarre, some say) effects and is sometimes used for scientific applications because it provides a consistent angle throughout its 180° field of view. OK, well it could be used for scientific purposes but mostly it’s used to give weird ’cow’s eye view’ scenics: think about it—you take a picture, turn around and take another picture, and now you’ve got a 360° panorama. This is not simply an ultra-wide angle lens. Circular fisheye means the image is a circle in the center of your frame, it does not cover the entire frame. If you’re not looking for a fully circular image, please don’t rent it or you’ll be unhappy.