Zeiss's Contax full-frame fisheye — the F-Distagon T* 16mm f/2.8, manual-focus glass for the C/Y mount.
The Zeiss F-Distagon T* 16mm f/2.8 was a full-frame fisheye lens for the Contax/Yashica mount, introduced alongside the early Contax SLR system in the mid-1970s. The F prefix marked it as a fisheye variant of the Distagon retrofocus family.
This is a manual-focus C/Y-mount lens with a 16mm focal length and a maximum aperture of f/2.8. As a full-frame fisheye it projected a curved 180-degree diagonal image across the frame rather than a circular one. Element counts and other figures are omitted where they cannot be verified.
The 16mm fisheye produces the bowed horizons and strong perspective characteristic of the format, useful for dramatic wide interiors, creative landscape work and effect-driven images. Its bright f/2.8 aperture made composing and focusing easier in dim conditions.
Used copies are uncommon and priced accordingly. Inspect the exposed curved front element carefully for scratches and coating damage since it cannot take conventional screw-in filters, and check for haze, fungus and clean aperture action. A C/Y adapter allows use on mirrorless cameras.