This lens made by Sigma under name of Carl Zeiss Jena II 28mm f2.8 Macro, surprisingly good lens I believe better than similar East German lenses like Pentacon 29mm f2.8. Easy to catch the right focus, well built quality lens. This lens has eye catch looking I like it very much even if I know this is not a genuine CZJ lens. Before communism was end in East Germany and in CCCP their sold their valuable brand name likes Carl Zeiss Jena and Helios etc to Japanese third party makers. I suppose Carl Zeiss (West German company ) wasn't happy at all :( This lenses are very rare if missing part of your collection don't hesitate much.