Herschel, I think the "trial-and-error" (or as you say analogue) way of finding
the best rotation point is the most efficient and practical way. The location of
the point seems to depend on a number of things and accounting for them all is
probably not a simple matter if you don't have information about the internal
design of the lens. And even if you do it is not simple! - andy
Herschel wrote:
This is interesting. I use the fancy manfrotto QTVR set up with levelling head
and 2-axis displacement sliding arms etc.
I have done some experimentation with different lenses and I think you're on to
something here.
I must go back and look at the numbers more carefully because when I first
started using it I used a 50mm lens and calculated where the nodal point was,
then used that as a starting position and it wasn't quite right. I attributed
this to errors in my measurements and the fact that lenses for 35mm cameras had
complicated optical arrangements etc.
But it makes sense to me, geometrically at least, that it's some other (Exit
pupil point?) place. How do you calculate the position of the exit pupil... is
it the aperture? I used the broomstick experiment that Walter talked about...
which gave me what I wanted in a rather "Analogue" way
