Sigma said that the development of lenses for the Sony FE system is now one of their priorities.
He says “Sony already has a 55mm f/1.8 which is nicely sized and reasonably priced, so why make another? But F1.4 compared to F1.8 is a huge difference, so we’d either make a F1.4, or something different.”
We can easily expect a Sigma FE 50mm f/1.4 ART version for the Sony A7 series full frame E-mount cameras. See below for the interview details.
Sigma says they will make lenses for the Sony FE system
From the interview:
A lens like Sony’s Zeiss 55mm F1.8 for the FE mount is optically superb but quite small and light. If you were to design ‘Art’ lenses for that system, would you try to strike a different balance between quality and size, and try to make the lenses smaller?
Yes – that’s also one of the segments we’re interested in. Another motivation for us to make new lenses is to differentiate between other manufacturers. Sony already has a 55mm F1.8 which is nicely sized and reasonably priced, so why make another? But F1.4 compared to F1.8 is a huge difference, so we’d either make a F1.4, or something different.