Hi--

I inherited a Nikkor PC lens but know nothing about how to use it. What is the purpose of the axis shift?
"Ron Smith"

Normally the circle of coverage of 35mm lenses barely covers the
1"x1.5" rectangle of the image area cropped out of it. With a PC
lens, the circle is much larger, allowing for the relatively
smaller cropped image area to be moved around inside the circle.
By definition, vertical lines remain vertical in the image only
when the true horizon line runs exactly through the center of the
circle of coverage and therefore, with most lenses, through the
center of the image. If you want to look up at a building or
down at a landscape and keep the verticals vertical (and parallel)
in the image, you cannot tip the camera; you must shift the lens
on the level camera to change the view up or down, the purpose
of the shift on the PC lens...