A short question about the Nodal Point of non extending zooms:
For (non-extending) zoom lenses like the Canon 17-40mm f4.0 L or 70-200mm f2.8 IS II L do you know if the nodal point shifts when zooming, or is that dependable from each lens's construction and cannot be generalized.
If your interest is in multi-frame panoramic photography, you have no reason to be concerned with either of the two nodal points
of a lens. They are not relevant to that issue.
You do need to be concerned with the often-called "no-parallax point", which falls at the center of the entrance pupil
of the lens.
Note that you can look into the lens from the front and locate this. It is where the aperture diaphragm looks to you as if it is
looking from outside the lens in the front.
I just took a quick peek into my Canon EF 70-200mm f/2.8L IS. It does not look as if the entrance pupil moves much (if at all) when changing the focal length.