Quote Originally Posted by aussieboy126 View Post
Just a question - are the horizontal and vert shift parameters always the same for the 16mm lens?
In theory - yes. In practice, mechanical tolerances in the lens and camera mount are such that variations are likely to occur when any physical changes are made (unmounting and remounting the lens, altering the focus setting etc.). In addition, the optimizer may evaluate slightly varying values depending on control points placement and compensating for minor parallax effects.

John