The Samyang 10mm F/2.8 ED AS UMC CS is currently a prototype lens that will be on show at photokina 2012.
The Samyang 10mm f/2.8 ED AS UMC CS is an ultra wide-angle prime lens designed for use with cameras that have APS-C / DX sensors. Its extremely short focal length and rectilinear imaging system ensure a wide angle of view, amounting to 110 degrees (~107 degree for Canon version). As a result the lens is a comprehensive tool for architecture and landscape photography. The Samyang 10mm f/2.8 ED AS UMC CS gives an equivalent focal length of 15mm (or 16mm in the case of Canon EOS) in 35mm terms.
All details concerning the optical construction and mounts will be published at a later date. The lens will be available at the end of 2012.