Master SLR, can you teach "shifting axis" in detail?

It is wasteful to use shift lens for ordinary SLR cameras.

The shift lens used in large and medium format cameras is almost the same.

Shift-axis camera lens is a kind of camera lens that can adjust the perspective of the captured image or focus the whole area. The most important feature is that the main optical axis of the whole camera lens can be translated, tilted or rotated on the premise that the plane position of the camera body and the film remains unchanged, so as to adjust the perspective relationship of the shot image or focus the whole area. The reference clear image field of the camera lens with shifting axis is much larger, which is to ensure that the camera lens can still get a clear image after its optical axis is translated, tilted or rotated.