Sigma has just announced the Sigma 20mm F/1.4 Art Lens which is officially the widest focal length f1.4 prime lens available. This lens brings the quality we have enjoyed from Sigma's Art collection to another focal length. Availability is set for mid November at $899. 

Pre-order Sigma 20mm F/1.4 Art Lens:  B&H Photo  |  Adorama     

From Sigma:
Comprised of 15 elements in 11 groups, the lens design includes two "F" Low Dispersion (FLD) elements, five Special Low Dispersion (SLD) elements, and two aspherical elements to significantly reduce chromatic and spherical aberrations, as well as limit distortion for clean, sharp, and evenly illuminated imagery. A Super Multi-Layer Coating has also been applied to minimize surface reflections, flare, and ghosting for increased contrast and color accuracy. The wide focal length and consistent image quality make this lens especially suitable for landscape, interior, architectural, and astrophotography applications, while the fast f/1.4 maximum aperture deems it ideal for natural and low-light shooting.