Sigma has released a 20mm wide angle lens. It is available in Sony E-Mount and L-Mount. It has 17 elements in 15 groups, a 94.5° FOV (in air) and a minimum focus distance of 23cm/9.1in. Performance behind a dome port is as yet unknown.

From Sigma

An Art level 20mm F1.4.

The ultimate lens for astrophotography.

Outstanding optical quality and a range of invaluable features – The ultimate astrophotography lens from the 20mm F1.4 pioneer The F1.4 series represents the SIGMA Art line, which pursues the highest optical performance and rich expression. The full-frame SIGMA 20mm F1.4 DG DN | Art is a mirrorless version of the SIGMA 20mm F1.4 DG HSM | Art; the one and only lens* with its unique specification of maximum aperture of 1.4 and an ultra-wide angle of 20mm. This lens offers photographers overwhelming optical performance and unlimited potential for ultra wide-angle creativity at a compact physical size. The exceptional F1.4 brightness and the breathtaking sharpness across the entire image even at maximum aperture make this lens the ultimate choice for astrophotography. In nightly darkness and focused to infinity, the 20mm F1.4 DG DN | Art captures stars in the sky as clear, precise pinpoints of light. State-of-the-art optical design and the large, high-precision double-sided aspheric glass front element made it possible to add a front filter thread without any compromises regarding optical performance or size. The addition of other invaluable features such as a rear filter holder and a variety of useful switches further increases the creative possibilities and easy usability of the lens. Its incredible sharpness and very bright aperture, coupled with the compact body and thoughtful features, make the SIGMA 20mm F1.4 DG DN | Art the ultimate lens for astrophotography and an ideal companion for any photographically demanding situation.

• As an AF interchangeable lens for mirrorless cameras that covers 35mm full-frame (As of August 2022, by SIGMA)