The Sony E-mount Sigma 15mm f/1.4 Fisheye DG DN Art Lens is a diagonal fisheye that brings epic scope and sweeping clarity to astrophotography, architecture, and landscape photography. With 21 lens elements in total arranged in 15 groups, including four FLD elements, three SLD elements, and two aspherical elements, the lens construction optimizes the reproduction of bright points of light. It also means the lens is sharp across the entirety of its viewing angle. The two rear sheet filter slots and the included Arca-Swiss compatible tripod collar benefit the long exposures necessary for astrophotography. Additionally, its dust- and splash-proof body and the water- and oil-repellent lens coating means the lens can withstand exposure to the elements. The HLA (High-response Linear Actuator) focusing motor introduces unprecedented speed, precision, and silence into the Sigma autofocus system. For videographers, focus breathing is minimized through the optical design.