Ken,
I am not 100% on this but it turns out that rotating about the rear nodal point is
something required for "swing lens" cameras such as the Panon or Panoram (if you
remember that far back!). When you do this the image remains stationary at the
image plane.
But when you rotate about this point (along vertical axis for sure) it turns out
that the positional relationship between foreground and background objects changes
as the camera turns.
This is not the same thing as the image moving ... well, it does in a way ... it
simply (?) means that when the camera is looking to the right (foreground vs.
background objects) objects at the left appear in a different location with respect
to each other. For rotating lens cameras the changes in position of objects is of
no consequence if it happens while the camera is rotated ... as long as at the time
the slot passes over a given line in the scene the subjects do not move relative to
each other. But before or after that time it does not matter.
So the camera needs to be rotated about something other than the rear nodal point
to keep the relationship between foreground and background objects fixed. This would
be a rotation axis running vertically through the lens at some other point than the
front or rear nodal point. If I read "stuff" about this correctly this would be
the center of perspective or the "entrance pupil" of the lens. I call is a "magical
point" or axis. ;)
Anyway, maybe a list member with experience with tripod heads such as the Kaidan
can further enlighten us on this topic. No?
andy
PS: written in a hurry just before leaving for a party!!
Ken Sinclair wrote:
Sir Andrew of Rochester,
If my aging memory serves me well enough, I believe I was taught that
the for panoramics (by camera rotation) the 'rotation point' had to be
dirtectly
under the nodal point of the lens.
Now... where did I leave my specs?
Ken
On 11-Apr-09, at 11:38 AM, ADavidhazy wrote:
trolling of course! (forgive me if you can!)
http://people.rit.edu/andpph/text-panoramic-bar.html
again, it turns out it is not new ... written off the
top of my head and there is not much there anymore!
;)
andy
Quando omni flunkus moritati (R. Green)
