Consider a photographer with an SLR camera and a PC lens placed in its predetermined position, without displacement, standing on the ground at the base of a building with columns whose height is X times that of the person and is at Y feet of distance from him.
The photographer composes a frame with the center of the building in the center of the frame with some empty space on top, to do so they have to tilt the camera slightly upwards, which creates a key effect with the columns that seem to converge vertically towards a point above of the frame
Then the shooter
maintains camera orientation level the camera and adjust the PC lens shift until the columns appear parallel in the image.
Is there any change in the focus at the bottom of the columns and the focus at the top of the columns before and after the change?