Asobinet.com dug up a few Sigma lens design patents, mostly featuring f/1.4 prime focal lengths that would presumably be mirrorless Art lens series replacements. But one stood out: a 28-70mm f/2 zoom monster akin to Canon’s lens of the same aperture and zoom range. That lens still costs more than $3,000 and was frequently on backorder even before the current supply chain problems started in earnest.
The patents specifically mention that a prime design objective and function of the patent was to minimize the size, weight and pull of the focus group of elements, allowing for quicker focusing and better image stabilization. The DSLR versions of the Sigma Art series typically did not have image stabilization.
Sigma’s mirrorless redesigns of its Art series have included more features (their excellent 35mm f/1.2 shown at left), but have been available only in Sony E mount and Sigm’s L mount until they recently started adding Fuji X mount as well. Plans for Canon RF and Nikon Z mount additions have been hinted for at least two years without any products surfacing.
Other designs include 35mm, 20mm, 24mm – all in f/1.4 – as well as a a 14-30mm f/4 zoom.