This circular fisheye lens produces circular images with an angle of view of 180° when attached to a full-frame digital or 35mm film SLR camera. It has a maximum aperture of F3.5, a minimum focusing distance of 13.5cm (5.5") and a maximum magnification of 1:4.6. The special fisheye design allows maximum creative expression. Sigma's super multi-layer lens coating reduces flare and ghosting, a common problem with digital cameras. The new lens power layout reduces color aberrations. Providing excellent image quality for digital and film SLR cameras. This lens can be used for the scientific applications such as the solid angle measurements of cloud distribution over the sky, the vegetation distribution of the rain forest canopy, etc., due to the quantifiable angle/area relationship it produces. This lens has a gelatin filter holder at the rear, allowing the use of gelatin filters.