mainshipper Loc: Hernando, Florida

Ah, Nodal point. That’s what I call it.

BboH Loc: s of 2/21, Ellicott City, MD

We're together albeit at different parts of the same definition:
Nodal Point - that spot on the ground directly under the center bar.
No Parallax Point (NPP) - that spot in the lens where the light crosses from top to bottom, from side to side and which must be directly above the Nodal point as the plum falls.

And I overlooked that you have an R-1, as I do. The neat thing about that that is that the NPP is directly over the Nodal Point without any adjustment. Its the M-1 that has to be calibrated. The offset, in my mind, about the R-1 is that each lens has to have its own mount. With the M-1 I can use any lens and I reserve the R-1 for my 8-15mm fisheye lens.