I have a flektogon, built for my Werramatic, so I don't have an aperture ring as the aperture ring is built into the camera, as far as being smooth in focusing it is fine, and opitcally it is fine, It may have been made in the GDR, but it is a Zeiss lens, and you won't go far wrong with the glass, it all depends on how the lens has been looked after, get one that was cared for and it is a very good lens indeed, and still features in the Zeiss line up, or did until recently, but get an old lens that has been abused and you will get a problem,the lens could be upwards of 50 40 to 50 years old, grease can thicken,Etc, I can't compare mine to a takumer as I have never used them, but I can compare them to other German lenses and they are, to my mind, fine lenses