Sigma 8mm f/4 EX Fisheye - Sigma SA, Canon EF, Nikon F, Sony A, Pentax K Mount

The Sigma 8mm f/4 EX Fisheye is a circular fisheye lens designed for full-frame cameras, producing a distinct circular image centered in the frame with a 180-degree angle of view. It is primarily utilised for creative ultra-wide photography, 360-degree panoramas, and scientific applications. The lens features a fixed petal-type hood and a gelatin filter slot at the rear, as the bulbous front element precludes the use of standard screw-in filters. Used examples should be carefully checked for scratches or coating wear on the highly convex front element, which is vulnerable to impact. The aperture blades must be free of oil to ensure snappy response. SDS verifies the mechanical integrity of the focus ring and checks the rear filter holder. The matte 'EX' coating on the barrel should also be inspected for signs of heavy wear or degradation common in this era of Sigma production.