The Zorki-4K was produced from 1972 to 1978 with a production of 524.610 cameras (Princelle also mentioned 36 produced in 1980). The 4K is fully identical to the Zorki-4, but with a rapid advance lever. In almost all cases this camera came with the Jupiter-8 lens (which is a Zeiss Sonnar clone) of very good quality. The 4K seems to be more an "export" camera. Cyrillic Versions are known. The 4K was produced after the Mir [2].
