Benn away for a while...

Finally got a D3s and managed to get the Nikon 24 mm TS-E shift and tilt lens. Using what I understand to be the method to get the nodal point I got the values of A=86 and B=115 (lower/upper rail). However taking a pano the other week at this setting, the join in PTGui was a little off. On top of that, I used the full shift up and down (10-11 mm).

A number of questions has arisen:

1. Is my figure of 115 correct for the upper rail. Does anyone have a different setting.
2. Is there anything particular to consider when using a TS-E lens, but only shifting in the vertical plane.
3. The figure of 115 was determined with no shift on the lens, in fact just like using a normal 24mm lens. Do I have to many different calculations for a chnage in the vertical shift.
4. Would PTGui have a problem stitching a pano if the 'film' plane is vertical (no lens distortion to really take into account).

If anyone has any experinece in using one of these lenses, and feedback you may have would be much appraeciated. I'll have another go at trying to get the upper rail figure a little later.

Thanks in advance,