proj-imim:
Re: Tilted monopods
Peter Murphy 2000-Jul-15 11:51:03
Yes Helmut, the lens against the wall method works
a treat - that way you can rapidly adjust the requisite tilt
for different monopod heights - one might need of course to
pull the base of the monopod away from the wall a little -
the distance of the front of the lens cap to the rear nodal
point if that distance is significant. I use an L bracket on the
tilt head for vertical shots. Once set up as above I lock off
the tilt head hard - then in the field I screw on the camera to
the base plate of the Lbracket (vertical now) and swivel the
camera til I can actually see the monopod base in the viewfinder
- if I can just see it I know the camera is now square on to
the L bracket to which I have fixed the bubble. Then depending
on the subject I might tilt the camera up or down relative
to the bracket - so the bracket stays level - but the camera
is tilting - it will still be approximately nodal for small tilts.
Thus if nadir detail is important I might tilt the camera down
maybe 5 degrees, zenith important, up 5 degrees.
Then level visually the first shot (get horizon in centre frame)
with the Adjust tool and have nonzero Image0 pitch and have
constant non-zero pitch for the sequence.
Peter Murphy
www.culture.com.au/virtual
Helmut Dersch wrote:
>
>
> 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