This circular fisheye lens produces circular images with an angle of view of 180° when attached to a full-frame digital SLR or 35mm film SLR camera. It has a fast maximum aperture of F3.5 and a minimum focusing distance of 13.5cm (5.3"). Sigma's super multi-layer coating and Special Low Dispersion (SLD) glass provide excellent image quality for digital and film SLR cameras. The special fisheye design allows maximum creative expression. This circular fisheye lens produces circular images with an angle of view of 180°and also incorporates an auto focus system to achieve accurate focusing that might be difficult through the camera's viewfinder due to the extremely large depth of field. This lens is perfectly suited for low light conditions indoors or at dusk. This circular fisheye lens has a minimum focusing distance of 13.5cm (5.3") and a maximum magnification of 1: 4.6 making it particularly useful for close-up photography. Special Low Dispersion (SLD) glass offers effective compensation of colour aberration. Sigma's super multi-layer lens coating reduces flare and ghosting, a common problem with digital cameras and also creates an optimum colour balance. Due to the quantifiable angle/area relationship it produces, this lens can be used for scientific applications such as solid angle measurements of cloud distribution over the sky, or vegetation distribution of the rain forest canopy.