@matigo Not as rare as that. Pentax made a camera called the Auto 110 in the late seventies and early eighties. It was the World's tiniest S.L.R. with interchangeable lenses. I bought some of the (tiny) vintage lenses for it and adapted them for my modern digital. They’re cheap and easy to find. A third party company made a teleconverter for the Auto 110 lenses that is much rarer. I was starting to think I wouldn’t find one. Now I can photograph things farther (further?) away with those lenses.