blog added 09/08/2006

Getting the camera centred on the panohead

 
After putting a new screw thread hole in to my 360precision panohead, my camera wasn't centred on the panohead correctly. This is because the Canon 5D is taller than the Canon 10D which my set up was built for. This resulted in a slight left-right translation misalignment and therefore possible parallax errors in all my panoramas. Now this wasn't too bad because the Realviz Stitcher software I use has a sensor shift correction, which also can correct for some small misalignments in the panohead set up. The lens had already been placed at the correct position for the nodal point of that lens.
 
 
NOTE the following does not set the nodal point of the lens just checks that  your camera is centred about the rotation point of the panohead
 
This of course isn't ideal, so I had two options, buy the right bespoke panohead for my camera or modify the one I have.
 
The question is how to you know when you have the correctly centred your camera.
 
Well, Realviz Stitcher can help. When you take the two down shots to remove the side arm of the panohead, stitching these together show whether you are correctly have your camera centred over the rotation point.
 
The following examples illustrate what I mean.
 
1. Firstly an example from some files sent by another panorama photographer to me for help, he was having problems stitching his panoramas together, looking at his files I felt that his camera  wasn't aligned correctly. The down shot shows there is misalignment left-right and up-down. Ideally central screw thread should be in the same position for the two down shots.

down

2. Now my starting setup. Firstly, the background picture frame and ruler are aligned, so sensor shift has been corrected, but you can see that when looking at the actual panohead I have the up-down position correct, but the left -right is out, I think the circles of the panohead do not overlap, they should if the camera is centred without  error.

knh-down

3. So I decided to see if I could correct the left-right misalignment by adding some washer to add spacer separation to the panohead. This was easily done using steel washers as shown. I started with 4 washers (see picture below). You can see that the up-down hasn't been changed, but left-right has been translation has moved to the other side compared to above, too far the other way.

 
down4
 
4. Now with 3 washers, this is better:
 
down3
 
5. Now with 2 washers in place. The two circles of the panohead are overlapping well. So, I think the now have camera centred around the rotation point.
 
down2