This is a Carl Zeiss Jena M42 mount prime lens, the Tessar 4cm T F4.5. ☆ I understand this was the world's first wide-angle lens for 35mm SLRs. It's a rare gem, even in the used market. It's a very compact lens. I loved it because of its straightforward rendering, but I'm selling it now to switch equipment. ☆ I have confirmed that all functions are working. The focusing helix feels a bit stiff, but it wasn't noticeable to me within the scope of my personal use. Please refrain from purchasing if you are sensitive to used items. ◎ Regarding the exterior, there may be some scratches and signs of aging, but it's in remarkably good condition considering its manufacturing date. I believe it's fair to say it's a beautiful item. ◎ Regarding the optics, there is no noticeable dust and it is in good condition. I believe the light transmission is good. Carl Zeiss Jena