Rotation around the entrance pupil (nodal point) for more natural camera movements?

Question

Do camera movements where the axis of rotation is fixed around the entrance pupil (nodal point), seem more natural by not shifting the perspective or do we as humans not actually move our sight/see in this manner?

I also am not too knowledgeable on what nodal points are (beyond being the point when the rays intersect) and how come the entrance pupil is formed at the nodal point and why these points can lie outside of the optical system? I have read the wikipedia page on cardinal points but due to my lack of knowledge on optics and lenes, I am still note as confident in the matter. I would greatly appreciate it, if anyone could also perhaps explain, with at as much detail as possible, what these terms mean in regards to camera systems.

Answer 1

This question was originally tagged cinema, so to a degree, the first part of your question isn't really on-topic for photography. But inasmuch as it intersects with photography:

As you indicated, rotating the camera about the entrance-pupil (a.k.a., 'no-parallax point'; a.k.a., 'nodal point') (but the latter is a misnomer), eliminates perspective or parallax shift. In photography, this is useful when stitching together several shots to make a wide panorama, because, assuming no motion in the scene between individual shots of the stitched pano, it's easiest to pick the overlap section and perform the stitching with minimal (ideally, zero) masking or adjustment.

But static shots, even wide panoramas, don't have anything to do with head movements. From a cinema standpoint, it's merely an artistic choice few people will notice. Think about human physiology: our eyes are inset at the front of our skulls, far in front of the vertebral stack. Our heads rotate around the vertebrae, thus causing perspective shift and parallax in our vision. (This is of course, separate from, and in addition to the simultaneous parallax we have with binocular vision).

In my experience, most videographers or DOPs don't set up their cameras and pan heads to rotate around the lens's entrance pupil; they're usually set up to place the camera's center of mass over the rotation point. This is just to make camera movements faster and safer and easier to control. Much like photographers with long lenses mount them balanced on top of the ballhead or on photo gimbals; it's the most mass-neutral position.

Answer 2

Human vision is binocular at short distances; and when we turn our heads the point of rotation is behind our eyes. It is nothing like a camera rotated around the nodal point.

Understand that the nodal points are where they appear to have effect. Similarly the entrance pupil's size and location are determined by how it appears.

If you look into the lens from the objective end you will see the aperture as magnified by the lens... you can judge its' apparent location and size relative to the lens, but it will not be the actual size/location of the aperture diaphragm. The apparent size/location of the aperture restriction is the entrance pupil, as that is what is relevant to the rays entering the lens from the objective end.

Likewise the rear principle point is the lens' focal length measured from the rear focal point back towards the lens/subject. A telephoto lens is designed to have magnification (focal length) greater than its' physical length... i.e. its' rear principle point lies outside of the lens.

Most drawings simplify this as being relative to a single element rather than a multi element lens assembly. These drawings are more representative of modern lenses.

Answer 3

Technically, we measure subject distance from the front nodal, however often depth-of-field tables and engraved on the lens depth-of-field scales are based on image plane-to-subject distance. Similarly, focal length is measured, rear nodal to image plane when the camera is imaging objects at infinity such as a star. Light from objects at infinity arrive at the lens as parallel rays.

A special circumstance is imaging with a panorama camera. The Panorama Camera is a special use imaging devise. Its purpose is to image large groups of people and to make extremely wide-angle landscapes with little or no distortion. The Panorama Camera sits on a motorized mount. The lens used covers only a small field. As the exposure progresses, the camera is caused to swing around a point which is the rear nodal of the lens. Such a scheme makes super wide-angle picture with little or no distortion.

To succeed, the mount pivot point must be exactly in-line with the rear nodal of the optical system.