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Nikon 5000 Nodal Points

These are the nodal points for the Nikon 5000 normal lens, wide angle lens, fisheye mode one and fisheye mode two.
normal lens nodal point
normal lens nodal point		 Wide angle lens nodal point
Wide angle lens nodal point		 Fisheye mode one wide angle nodal point.jpg
Fisheye mode one wide angle nodal point.jpg		 Fisheye mode two (rectangular) nodal point
Fisheye mode two (rectangular) nodal point

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Daniel Griscom 07-Sep-2003 10:35
I saw your very clear nodal point images for the FC-E8 fisheye adaptor, and it didn't make sense to me. The nodal point is (in theory) where all possible light paths from the outside world through the lens to the detector intersect. Your diagrams show that, when viewed from the side, the light path to your nodal point doesn't even go through the glass of the lens! This means that light from the edges of the FC-E8's FOV must converge at a nodal point forward of yours (by at least 10mm, which is the distance to the glass).

I tested this using a cheap pen-style laser, tracing the nodal point paths for the full 180+ degree FOV (using fisheye mode 1). What I found was that your nodal point measurement was right on the money for the central 110 or so degrees, but outside that the nodal point started to move forward, until at the margins it is 10mm forward of yours. In other words, the FC-E8 lens doesn't have a single nodal point across its FOV.

It's difficult to know how to use this information. Probably, if using two fisheye shots to cover a panorama, you should use the more forward measure of nodal point, since it's correct at the edges and there's where you'll be joining your images. But for work where you use three or more images the rear nodal point would work better.


Thanks,
Dan
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