On the Bertele: The lens element does not float to counter focus shift.So the lens elements float to counter focus shift?
Chris does use an indexed cam to counter a change in focus when the lens is used at nearest focus.
I did discuss an idea that could be implemented for correct focus shift: couple the Aperture Ring with the Barrel. This could be done on a Jupiter-3 by fixing the aperture ring into position with the focus mount and turning the entire barrel to set the F-Stop. The Aperture ring of the J-3 (and 5cm F1.5 Sonnar) is screwed into the barrel using a fine thread. The barrel moves relative to the Aperture Ring. Construct it so it moves to correct the focus shift.