The Nikkor-O 55mm f/1.2 CRT lens was produced in the early 1970's by Nikon to take photos of oscilloscope screens. This very rare speciality lens was made for industrial use to record faint cathode-screen traces and came with a long Leica Thread mount. It can be mounted on any Nikon camera with the LF adapter and a restricted focusing range is achieved by rotating it in the adapter. Alternatively, it can be modified by a master technician and converted to Leica M mount to be used on Leica Rangefinders.

The uniqueness of Nikkor-O CRT 55mm f/1.2 lens is not because of its curvature as used in monitoring CRTs but how incredibly sharp and good it is at resolving images. Once converted to Leica M Mount, the unique character is completely presented through its motion-like bokeh provides a sense of movement for still images.