pivot on vertical axis.
moves the centre of the image circle to the left or right
of the centre of the film. However, the swing
does not change which section of the image circle is recorded
on film since the optical centre of the lens and the centre
of the film stay aligned.
and tilts of the lens standard have NO effect on perspective,
but they alter the plane of focus. (Just remember in a
normal camera we focus with the lens)