Sigma 4.5mm f/2.8 EX DC HSM Circular Fisheye Lens for Canon Digital SLR Cameras Fast F2.8 maximum aperture making it ideal for low light photography Minimum focusing distance of 13.5cm and a maximum magnification of 1:6, Focal Length - 5 mm Equisolid angle projection method is possible for art and scientific use Equipped with HSM with full-time manual focus override