Minolta's full-frame fisheye — the MC Fish-eye Rokkor-OK 16mm f/2.8 from the mid-60s MC line.
The Minolta MC Fish-eye Rokkor-OK 16mm f/2.8 is a full-frame fisheye manual-focus lens for Minolta reflex cameras, from the MC generation that introduced meter-coupling to the Rokkor line in the mid-1960s. The Fish-eye designation marks its ultra-wide, deliberately curved projection covering a diagonal of about 180 degrees on the frame.
This is a manual-focus full-frame fisheye with a 16mm focal length and a maximum aperture of f/2.8, part of the MC series that added meter coupling to the mount. The OK code encodes the element and group arrangement in Minolta's system. Only the focal length and aperture are affirmed; other construction figures are not confirmed here and are omitted.
As a fisheye the 16mm renders an extremely wide field with the characteristic curved-line distortion, filling the whole frame rather than producing a circular image. It suits creative wide interiors, dramatic landscapes and architectural effects where the bowed perspective is used intentionally, and the f/2.8 aperture aids composition and low-light framing.
On the used market this MC fisheye is an uncommon specialist Rokkor sought by collectors and creative shooters. Given its age, inspect the exposed front element for scratches and cleaning marks, check for internal haze, fungus and separation, and confirm the aperture and focus operate smoothly. Note that its bulbous front element cannot take conventional screw-in filters.