When taking photographing starry skies or other night-time celestial scenes, or the seashore with a wide perspective, a large-diameter lens is a strong ally. It allows the capture of a moving subject by adjusting shutter speed without relying on ISO sensitivity. With full-frame 35mm coverage, 14mm ultra-wide angle focal length, f/2 barrier-breaking f/1.8 aperture, the Sigma 14mm f/1.8 DG HSM Art is the high-speed, ultra-wide-angle lens photographers have been waiting for. Although some zoom lenses are available that can cover 14mm, the large diameter delivering f/1.8 brightness is a singular advantage. Going beyond fast shutter speed, this lens can capture a swarm of fireflies with crystal clarity, a beautiful bokeh effect, and outstanding control of light streaking. Art Lens Engineered for those who see photography as a critical expression of self, Sigma's Art line offers sophisticated optical performance and abundant expressive power to deliver faithfully on your artistic vision. DG for Digital Designed to deliver the ultimate in performance on full-frame digital SLRs, Sigma DG lenses also bring out the best in 35mm SLR film cameras and APS-C size DLSRs. Aspherical Lens Elements (ASP) The aspherical lens complex allows freedom of design, improved performance, a reduced number of component lenses and a compact size. Hyper Sonic Motor Focusing (HSM) HSM lenses employ a motor powered by ultrasonic waves that produce a quiet, yet high-speed AutoFocus. You can enjoy high performance with low noise in a variety of shooting situations. Inner Focus (IF) To ensure stability in focusing, this lens moves the inner lens group(s) without changing the lens' physical length. 14mm Ultra-Wide-Angle and f/1.8 Brightness By leveraging its extreme angle of view and the dramatic perspective this creates, an ultra-wide-angle lens can get up close and personal with a subject while at the same time taking in a vast background-an example of photography going beyond normal human vision.