The Sigma 14mm f/1.8 ART has a unique combination of ultra-wide field of view paired with a larger-than-average f/1.8 maximum aperture. This makes it an ideal lens for various astrophotography uses such as aurora photography, Milky Way photography, star trails, time-lapses and general nighttime landscape images.
As is normal for Sigma ART models, the lens is available with all of the major mount types, although Canon and Nikon mirrorless users will have to use adapters from the EF mount and F mount versions respectively for now at least. The lens is also eligible for the Sigma mount conversion service, so if you change camera brands, you can send the lens in to get the mount converted to your new cameras.
I purchased this lens myself, and in time I will post a full review. In the meantime, I wanted to post a gallery of hands-on photos so that people can get a good look at this interesting lens.