Interestingly, I had (still have) some old screw-mount Takumars. I also had some quite clean screw-mount Pentax bodies (S1a, SV, Spotmatic) but I never could get a sharp picture because of their vibration levels. I got rid of the cameras but still use the lenses sometimes on a Bessa L (Leica-type non-rangefinder camera) with an adapter. On this body the lenses are really sharp!