Carl Zeiss Jena Tessar 50mm f/2.8

"Tessar" is from the Greek word τέσσερα (téssera, four) to indicate a four-element design. Tessar lenses provide good optical performance at a reasonable price. They have been around since 1902, although only since 1930 have they been available in apertures as big as f/2.8.

Canon EOS 20D and Carl Zeiss Jena DDR Tessar f/2.8 M42 50mm lens.