Nodal
In the context of CinCraft Scenario, the “Nodal” point refers to the point of no parallax of a lens.
When the camera is rotated around the nodal point, then objects in the foreground and background will stay consistent relative to each other, in other words, no parallax shift is seen.
This stage of the calibration allows a user to input a single nodal point (or two if calibrating a zoom lens). At the final stage of the calibration, it is possible to add more nodal information if required
The nodal point can be measured externally of the CinCraft system and the premeasured values can be simply input at this stage. If the nodal point needs to be measured however, the following process can be used.
Align two posts/poles in front of the camera, the first pole (blue) relatively close to the camera and the second (red) relatively far away.
Ensure the camera is aligned centrally with posts. When setup correctly the camera should be looking directly at the poles in the centre of frame, with the first pole occluding the second pole.
Pan the camera so that the poles are on the edge of the frame, it is likely that a gap has appeared between the poles caused by the parallax.
Slide the camera forward or back on the tripod head (a long slide plate can help with this) while making panning motions until no visible shift is seen between the two poles.
Once this position is found, measure from the camera sensor to the point of rotation of the tripod, this will give you the nodal value for this part of the lens.
