Samyang is known to build lenses with high optical performance and these lenses have to operate manually. There is a confirmed rumor about Samyang prime lens. Samyang is working on a 50mm f/1.2 lens to be released in 2014.
In a recent post on their Facebook page, Samyang Asia mentioned that a new 50mm f/1.2 lens is on their roadmap for 2014. The lens will be available for Canon, Nikon and Sony mount.