What, no 500mm ApoTessar?????????There is an S adapter with no electrical or moving mechanical connections. So what do our elder brethren provide? The 250/5.6 and 350/5.6 Superachromats and the APO teleconverter 1.4XE. With Dante as my Virgil (think about that...), I got my hands on both of those lenses and have had a few weeks with the 250 and a few days with the 350, and I can report a few things.