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Figure 13 Adjust camera height position
Adjust Camera No-Parallax Point
Where is the No-Parallax Point? The physical location of the optical center is unique for each lens. For
prime lenses, the No-Parallax Point (with focus at infinity) is stationary. For zoom lenses, however, the
No-Parallax Point typically shifts for each focal length. The location of the No-Parallax Point is
commonly expressed as its distance, in millimeters.
Adjust the camera position based on the total entrance pupil distance. This number is the sum of the
camera length number, (the distance between the middle of the tripod mounting hole to the base of
the lens base, or base for adapter tube,) and the entrance pupil distance of the lens.
For example, the length number of a Canon EOS 5D Mark II is 38.5mm. The entrance pupil distance of
a Canon EF 16-35 F2.8 lens is 79mm at 16mm focal length. Therefore, the total entrance pupil distance
(or NPP) is:
38.5mm +79mm=117.5mm.
Figure 14 Adjust camera entrance pupil position
Slightly loosen the Dovetail Saddle Locking Knob #16. Move the Dovetail Mounting Module #4 back
and forth so that the 117.5mm mark on the dovetail bar is aligned to the edge of the Camera Mounting
Platform #3 (refer to the inlet in Figure 14). Tighten the Dovetail Saddle Locking Screw #16.
Note: Zoom lens has different entrance pupil distance at different focal length.
You can find camera mounting hole off-center, camera height, camera length and lens entrance pupil
position parameter from panotools.org
(http://wiki.panotools.org/Entrance_Pupil_Database
).
A More Practical Way to Find the NPP
The NPP can be determined by experimentation. Here I show to do it:
13
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