A Sigma patent suggests the third party lens maker (relegated in the past two years mostly to a Sony E mount lens maker) looks to be formulating a very large aperture, very wide angle zoom lens.
Versions range from 15-18mm to 18-30mm, with a goldilocks version in the middle of 16-28mm. All all sport an f/1.8 aperture throughout the focal range.
While Sigma’s president has voiced the desire to include Canon RF and Nikon Z mounts in their manufacturing, this has been continually put off. Neither company makes a lens close to this bright in those wide ranges.
The popular Canon 15-35mm f/2.8 lens, shown here was considered among the brightest wide zooms practically available.