Sigma 4.5mm f/2.8 DC HSM Fisheye Lens - Canon
Sigma’s 4.5mm F2.8 EX DC Circular Fisheye HSM creates an image that is a circular, curved, distorted view of reality when used on a digital SLR camera. One of the most unusual lenses a photographer can use as it produces a circular image within a black surrounding frame. It is ideal for landscapes and panoramic photography. Because of its equisolid angle projection system, the lens can be used for scientific applications.