Big Ben's Panorama Tutorials

Determining the Nodal Point of a Lens

While it is not entirely essential to accurately position your camera for each image, it does make things a LOT easier if the lens is rotated as close as possible around its nodal point. By doing so, you remove parallax errors which may require a lot of retouching to make things look right in the finished panorama.

Determining the nodal point of a lens is quite easy to do visually.  You will need two vertical features to use as reference points e.g. a doorway, flag/light pole, corner of a all etc...  One must be very close to the camera, the other, far away.  You will also need an adjustable tripod pano head or a focussing rail to adjust the position of the camera relative to the axis of rotation. Accuracy will be in the order of 1mm for a circular fisheye lens.  Accuracy will be greater with the near object as close to the camera as possible.

The diagram below shows what happens in the three possible situations.  Note that the relative positions of the objects on each side of the gap is determined from the nodal point of the lens, not the axis of rotation.

Legend
 Rotation axis  Camera & nodal point
Rotation axis at nodal point
[diagram] Gap remains constant
Rotation axis forward of nodal point
[diagram] Rotating camera away from near object increases gap width

Rotating camera towards near object reduces gap width

Rotation axis behind of nodal point
[diagram] Rotating camera away from near object reduces gap width

Rotating camera towards near object increases gap width


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This page, its contents and style, are the responsibility of the author and do not represent the views, policies or opinions of The University of Melbourne. All photographs Ben Kreunen 2000

Ben Kreunen <bernardk@unimelb.edu.au>
Department of Pathology
Last modified: February 24, 2003