the first Perspective Control lens type that broke the 24mm barrier in 35mm SLR photography (1984).
due to its protruding and the extra large front element, the lens was designed with a built-in protective scallop hood to protect the front ED glass lens element.
an internal revolving filter turret supplies filters where a Neutral Density, Y48, O56, R60 are provided.
a beautiful lens that many architectural photographers bought and converted to Nikon mounts. It is reportedly much sharper than the Canon version, and once converted, will work in stop-down metering mode just like Nikon's PC lenses.