At Photokina 2018, Samyang shows off a new XP series lens XP 10mm f/3.5 full frame DSLR lens. This lens is currently world’s widest full frame DSLR lens. Currently no price and release date info, stay tuned.
From ephotozine:
The lens boasts a zero distortion recti-linear design and Glass Mold aspherical lens elements. Samyang say it will work with 50-megapixel high-resolution cameras.