A Note on the No-Parallax Point (Not Nodal Point)

Often, people will say that you need to rotate your camera around “the nodal point” of your lens to eliminate parallax when taking panoramas. Unfortunately, this is not correct for several reasons.

Firstly, there is not a single nodal point for a lens, in fact there are 2 (front and rear). Secondly, neither of these 2 nodal points is the point around which you need to rotate the lens to avoid parallax [1]. One should rotate the lens around the entrance pupil (the apparent position of the aperture stop) to avoid parallax. This position is also called the No-Parallax Point (NPP for short).

There are complications of course. The entrance pupil position can change depending on the angle at which the light rays enters the lens. This is especially noticeable in fisheye lenses where the entrance pupil can move significantly at extreme angles off-axis.

Peleng 8mm Fisheye Entrance Pupil Shift. (Left) The entrance pupil (the bright spot in the middle) when looking near the optical axis appears to be about a cm of two back from the front bezel of the lens. (Right) At nearly 90 degrees from the optical axis, the entrance pupil is at the same plane as the front bezel.

This shift in entrance pupil can occur in “normal” lenses as well but usually to a smaller degree. A more detailed examination of where the entrance pupil is located and can be shifted can be found here (pay attention to p.10 in particular). So the next time some says “nodal point”, gently guide them to use the term “entrance pupil” or “no-parallax point” instead.


[1] From Wikipedia: “The nodal points are widely misunderstood in photography, where it is commonly asserted that the light rays “intersect” at “the nodal point”, that the iris diaphragm of the lens is located there, and that this is the correct pivot point for panoramic photography, so as to avoid parallax error. These claims generally arise from confusion about the optics of camera lenses, as well as confusion between the nodal points and the other cardinal points of the system. (A better choice of the point about which to pivot a camera for panoramic photography can be shown to be the centre of the system’s entrance pupil.”