Btw, it is not the number of images that makes the 3D effect but the amount of forward shift out of NPP of the lens.
Shooting more images is better because this reduce the parallax errors that are always present when shooting images out of NPP.
F.e. when shooting a 3D pano with a normal number of 6 images for the round shots you could easily get control point errors of 40 px between the images, the resulting 3D pano would be awful to look at, especially close to zenith and nadir.
When shooting 10 times more images (60 instead of 6) the parallax error between the images is also 10 times reduced so instead of 40 px the CP errors are 4 px and this is often acceptable.
More images will almost(*) always give a better result so when in doubt how many images are needed you better shoot the highest number of images you can shoot and process.
(*) When shooting a 3D pano outside you often will take less images then optimum to speed up the shooting time, this will reduce the chance that objects will move in the scene (in an ideal situation objects are "frozen" when shooting a 3D pano with a single camera).
Last edited by Wim.Koornneef; 04-01-2014 at 06:44 AM.