http://www.trenholm.org/hmmerk/VuCamTxt.pdf!
Since we have unlimited DOF in 3D this subject pertains primarily to controlling shallow focus DOF but also helps with distortion. In C4D, adjusting rotation of the camera (Swing or Tilt) and then adjusting Offset (Shift) is essentially rotating the Film/Sensor Plane and keeping the Lens Plane perpendicular to it. You do not need the Protection Tag. It would be beneficial to be able to rotate the lens plane separate from the Camera/Film/Sensor Plane. Rotating any of these Planes changes the shape of the Subject Plane, so ideally all three planes should be rotated for less distortion and optimum focus. In the real world, the subject is often fixed so we only have the other two planes to adjust which is helpful but limited. In C4D, only the Film/Sensor/Camera Plane can be rotated which is helpful but more limited. On the plus side, we have unlimited DOF and X/Y Offset!
Here are some examples of how rotating the camera changes DOF and Subject Shape. The fstop(f2) and Focal Length (90mm) and Sensor Size (52.5) remain the same. The more Rotation (Tilt) and Offset (Shift) applied the more the camera needs to be pulled back to include the same subject area which also affects the amount of DOF. Sorry these down and dirty examples do not show the difference in focus very well. I should have placed the cylinders on a textured or otherwise detailed surface to show the DOF falloff better. On the full tilt example the surface is out of focus and only the tops of the cylinders are sharp.