1980 20 Mk Abbe, DCAM PR68DCAM 认证号84674458, PCGS号395532

Germany-Democratic Republic | KM# 78 | J-1575 | Commemorating the 75th obit of Ernst Abbe Ernst Karl Abbe (23 January 1840 – 14 January 1905) was a German physicist, optical scientist, entrepreneur, and social reformer. Together with Otto Schott and Carl Zeiss, he developed numerous optical instruments. He was also a co-owner of Carl Zeiss AG, a German manufacturer of scientific microscopes, astronomical telescopes, planetariums, and other advanced optical systems.