Shooting panoramas with a "virtual tripod"
When shooting photographs for later assembly to obtain 360° panoramas, you have to be very careful in pointing the camera to get good results:
The use of a tripod is an obvious solution, but it has some shortcomings:
Here is the setup I use to shoot spherical panoramas with a Nikon Coolpix 950 and a fisheye adapter. It requires only a spirit-level (bubble level), a thread, a weight andů a steady hand. Attach the thread with the weight to the fisheye adapter just behind the front lenses (the nodal point is located near this plane) and fix the spirit-level to a plastic piece (I used a CD-box) that you slide in the hinge of the Coolpix.
To take the photos (three, about 120° apart) position the weight just above a mark of the floor, level the Coolpix with the bubble and shoot. The rotation point of the camera is fixed in horizontal direction because it is above the mark, and in the vertical direction by the length of the thread. The bubble fixes the pitch and roll angles.
Don't forget to lock the automatic exposure and white balance to get the same colors between the shots.
To assemble the panorama, I use Panorama Tools, a great freeware package you can get on Helmut Dersch's web site: http://www.fh-furtwangen.de/~dersch