What principle can make an ordinary lens shift axis?

Shift-axis lens can eliminate perspective distortion, because when shooting tall buildings, the lens needs to be tilted upward to get a panoramic view. Results The film plane is at a certain angle with the main line of the high-rise building, and the upper part becomes smaller due to the long distance between objects, resulting in perspective deformation. After the axis-shifting lens is moved, the lens center does not pass through the film center, so the distance between the upper and lower parts of the film and the lens center is not equal. Although the upper object distance is far, the corresponding image distance of the lower part is also far, and the corresponding magnification change offsets the perspective deformation. As long as the film plane is parallel to the main line of the building, there is no perspective deformation in the photos taken. By shifting the axis and swinging, an inclined plane can be focused on the focal plane, so that the object on the inclined plane can be imaged clearly.

This is also an encyclopedia. Read it a few times more and you should get something. Secondly, you need to know something about the depth of field, because the focal plane has been adjusted, which leads to the change of dispersion circle and also produces a small depth of field. Understand the principle of depth of field.