I've spent days trying to get the nodal point right on my Canon EOS 20D/Sigma 10-20. I use PTGui as stitching software. No matter what I did I couldn't get rid of what seemed to be parallax errors. Then I suddenly discovered the advanced settings on the optimizer-tab, when I checked "Field of view", "a", "b", "c", "Horizontal shift" and "Vertical shift" under "Optimize globally" all of my panoramas got perfect (PTGui says "Too good to be true" when optimizing). Now I wonder if I actually have got the nodal point right or if there still is something wrong with my Nodal Ninja-settings that's getting corrected in the software? I want as much as possible to be optimized with hardware and not by some more or less "inaccurate" software-algorithm. Do you have problems stitching panoramas with PTGui without optimizing the horizontal/vertical shift?