Viltrox 16mm f/1.8 FE lens at BHphoto, Amazon US&EU and PerGear.
Also very reliable reviewer Opticallimits is impressed by the new Viltrox 16mm f/1.8 FE lens performance:
Many users may still not be aware of Viltrox as a lens manufacturer, but they are becoming a force to be reckoned with. The AF 16mm f/1.8 FE leaves the Laowa 15mm f/2 far behind in the dust. It’s a very serious alternative to Sony’s own offering. And Viltrox managed this at a much lower price tag. Therefore – Highly Recommended!