Hello Bob,

Forgot to mention ...
My 10.5mm is not shaved and is used withe lens hood still in place without any intrusion into the image.
Also, I use the gold ring as my reference for setting up on the top rail and do not take much notice of the numbers, so line up the gold ring with the vertical axis of rotation by eye.

http://hugha.co.uk/NodalPoint/Index.htm

http://hugha.co.uk/Acrobat%20PDF%20F...int-Clouds.pdf
Psge 7