When the camera is positioned above, below or at the side of the centre of a parallel structure like a building or painting, the structure will appear to tapper in the resulting image. This happens because the projected lines from the corners of the structure through the lens to the opposite corners of the camera frame are nor equal - we see this where X is longer than Y.
This can be corrected to a certain degree by using a longer lens and selecting a viewpoint much further back. As we see in A- B, this results in equlizing the projected lines - the ratio of the two is more even. |