As noted by many others M 42 glass as really gone up in the last couple of years. Just last week I was shooting at the Phoenix Zoo and someone offered me way too much money for my Super Tak 120mm, almost took it but I hate to sell off any part of my kit. Chinon made some nice basic M 42 that does not appear to have gone up all that much as Pentax, 28mm 2.8 35mm 2.8 50mm 1.7 135mm 2.8, Vivitar and Soligiar seem to hit and miss, some were very sharp others not so much. Yashica also make some sharp lens as did Fuji. Fuji line up was very good, I think they made as many M 42s as pentex.