Originally Posted by ragc
Whether 3- or 4-point pivoting, you won't gain a shift movement with that.
By the way, any perspective manipulation/correction is done with the filmback; a lens shift only gives the desired field of view.
Originally Posted by AgX
You are correct. My camera has front shift (rise/fall with the camera on it's side), so the device I made needed only to add tilt and swing.
The back controls perspective, but the front controls what is in focus. Remember I am advising him on how to obtain movements for a hypothetical viewfinder. He could use the same mechanism on the back as on the front to achieve this.
For my purposes, again, my camera had tilt on the back, so I needed the mechanism only on the front.
I do appreciate your clarifications, as it is clear that my comments were incomplete.