Nick: So that explains why I always get "breaks" in the ceiling and floor, because we can only optimize settings for horizontal view? And are u saying we can eliminate the ceiling and floor breaks by taking another 2 shots (one zenith and one nadir)? Thanks.

John: Well, with the Ultimate R1 and a known/common lens (namely Sigma 8mm f/3.5 Nikon mount), the given settings (by Nick) should already be free from parallax errors (only for horizontal view), isn't it? And in your article, you mentioned that the ideal should be 4 shots plus nadir and zenith (that's 6 shots in total). Could it be done with 3 shots plus nadir and zenith? Thanks.