8mm Sigma for Canon (Canon 7D in my case) NPP Question
I originally purchased the Sigma 4.5mm Canon lens made for the APS-C sensor for my Canon 7D with the corresponding ring for the R1 head. I got excellent results that stitched well in Easypano Panoweaver, PTGui and AutoDesk Stitcher (aka. Realviz) shooting 3 horizontal images at +5 degree tilt. I'm new to this kind of photography, so I sampled all the main stitching softwares and found them easy to use and provided good results.
Unfortunately I had not realized that even with an 18million megapixel sensor, the best resolution for the final pano is only 5624x2812 pixels due to the fact that most of the sensor is not exposed to the spherhical image produced by the 4.5mm lens
So I switched to the 8mm Sigma lens and the corresponding R1 Ring and now have a final spherical pano resolution of over 10,000x5000 pixels and I shoot 4 horizontal images instead of 3. (My many thanks to Nodal Ninja and Henry's photography for allowing me to exchange the gear).
However I am having very bad alignment problems. I mounted the lens in the R1 head following the directions as before, but none of the above softwares can perform and acceptable stitch.
Documentation states that NPP point is at 1.95cm for +5 degrees for the 8mm Sigma - Canon lens . So I questioned if the NPP value was correct and did some tests aligning a tip of a lead pencil with a distant object while rotating the camera and my observations indicated a NPP point of 1.55cm. However my stitch results are still terrible.
I would like to know if anyone else has had to use different NPP settings than indicated in the documentation, or are they considered good as gold? Is there a fundamental difference in how the software should be used with the new setup? Could the problem be with the lens? Or is the problem somewhere between the chair and the keyboard - me?
Any feedback would be much appreciated.