On Friday, August 31, 2001, at 06:24 BC, Mark Doolittle wrote:
and , Ted Oliverio at email@hidden wrote:
I'm not sure about your particular camera or lens combination, but
I've
never seen a rig where what you describe is true.
Typically, the nodal point is at the very-very front of the exposed
surface (i.e., film or CCD). We typically use The Parallax Test to
find
this spot, as it only takes a few seconds.
With my Nikon N90/16mm fisheye, the nodal point is within a few
millimeters
of the farthest front edge of the lens. Found by setting a light
stand a
couple feet in front of the lens, lining it up with a vertical across
the
room, and then sliding camera forward/backward until the light stand
and
vertical do not move relative to one another when the camera is
rotated on
the tripod. Is that the "Parallax Test"?
* Yes, that's the parallax test (the effect you were eliminating is
called "parallax")
* I stand corrected about fish eyes. I might've been wrong about the
nodal point being the front of the exposed surface, too -- maybe it's
the point where the rays of light intersect as they "flip" on their
way to the back of the camera (I often get these things confused --
another reason to run the parallax test, rather than do it from
memory :) Either way, I knew it wasn't "the very front of the
glass" -- I'm pretty sure you can't have a nodal point that's OUTSIDE
the lens.
