Budget Sigma telephoto zoom in rare Praktica PB mount, one of few telephoto options for the East German SLR system.
The Sigma 70-210mm f/4-5.6 Zoom-K MC is a vintage telephoto zoom for the Praktica PB bayonet mount — the standard bayonet used on Praktica SLR cameras from VEB Pentacon (East Germany) from the 1970s. MC = multi-coated optics. Praktica PB mount.
f/4-5.6 variable aperture. 70-210mm zoom range (full-frame). MC (multi-coated) optics. Manual focus. Praktica PB bayonet mount.
The Praktica PB mount was the bayonet standard introduced by VEB Pentacon (East Germany) to replace the older M42 screw thread on Praktica cameras. Third-party manufacturers including Sigma produced PB-mount lenses for the significant European Praktica SLR market.
On the used market the Sigma 70-210mm Zoom-K MC is a vintage Praktica PB telephoto zoom. Condition checks: zoom ring smoothness, lens elements, aperture blades. Praktica PB mount — manual focus. PB-to-mirrorless adapters available but uncommon.