Hi Dave,
It depends on where the tilt axis is positioned in the lens design. As soon as the entrance pupil of the lens shifts as a result of tilt, i.e. the rotation axis is not in the entrance pupil plane, then the image will shift a bit (the perspective changes). That small shift amount will cause a slight change in the ray's angles. So if the rotation axis is aligned with the entrance pupil of the lens, then nothing much happens other than the principle plane and focus plane rotation.
It's usually easy to see if the image moves when the lens is tilted, and one might want to compensate with an opposite shift to keep a given composition.
Cheers,
Bart
Yes, if you are performing axil tilt, the angle at which the light hits the sensor will not change. However, if you are performing base tilt, which is pretty much what you are doing with longer lenses on technical plate cameras, the angle will change since the position of the nodal point changes as well.
For instance with my RM3Di, my SK 35mm is mounted so the nodal point is very close to, if not right at, the axis that the helicoid tilts on. So tilt is really not going to change the angle of light hitting the sensor. However with my Rodie 90mm, the nodal point (and the lens itself) is a good distance away from the tilting axis. So tilting here will move the lens, changing the angle that the light comes in at.
Wow, I really need to proof read these posts in the morning.