Zeiss's Contax telephoto prime — the Sonnar T* 135mm f/2.8, manual-focus glass for the C/Y mount.
The Zeiss Sonnar T* 135mm f/2.8 was a telephoto prime for the Contax/Yashica mount, part of the Contax lineup from the mid-1970s and a common short-to-medium telephoto in the system. The Sonnar design kept it reasonably compact.
This is a manual-focus C/Y-mount lens with a 135mm focal length and a maximum aperture of f/2.8. The Sonnar layout gave a lighter, smaller body than the faster 135mm f/2 Planar. Further specifications are omitted where they cannot be verified.
At 135mm f/2.8 the lens works for portraits, travel telephoto framing and general reach, with good compression and a manageable size. It renders cleanly and is easy to handle for a lens of its focal length.
Used copies are plentiful and among the more affordable Contax Zeiss telephotos. Look for internal haze, fungus and coating wear, confirm smooth focus and clean aperture blades, and check the front element. It adapts to mirrorless with a C/Y adapter.