proj-imim:
Re: Tilted monopods
Helmut Dersch 2000-Jul-15 16:13:35
Peter Murphy wrote:
>
> Suppose you have a monopod and a one-way tilt head. If the tilt
> action is towards and away from you - ie a proper tilt not a roll -
> then you have a camera support system where the rear nodal point
> of the lens can be positioned so that it is directly over the monopod
> base
> when the camera is made level - ie what is needed for zero
> parallax panoramas. This means that the angle between the lens axis
> and the main axis of the monopod is less than 90 degrees. ie the camera
> and monopod have somewhat the profile of the figure 7.
> It is easy to set this angle if you know where the rear nodal point of
> your lens is. Then the only portion of your scene that is being
> obscured is the very base of the monopod which small area is
> easy to retouch.
>
I am using a similar setup for most of my panoramas, see this figure
<http://www.fh-furtwangen.de/~dersch/monopod.gif>
It is a variation of the method Andrew Nemeth describes at his website.
Fisheye lenses have nodal points close to the front surface of the
lens. This makes it simple to adjust the tilt angle using a vertical
wall, and moving the front lens (properly protected) to touch the
wall while the camera is kept level. Turning the monopod while
keeping the camera level then very accurately fixes the nodal point.
Problematic is the adjustment of horizontal pan-angles. Guessing
and letting the optimizer find the values works most of the
time. It is also possible to adjust manually, since after remapping,
this corresponds to horizontal sliding of the images against
each other in Photoshop.
Helmut Dersch