In architectural photography, the effect of converging lines is often unwanted and can be avoided by using a perspective control lens. This lens can be shifted out of the optical axis and thus the film plane can be positioned parallel to the subject and the subject is rendered undistorted. Shift lenses are mechanically and optically more complex than ordinary lenses, so they are comparatively expensive. The software ShiftN offers another way to correct converging lines. All corrections are done automatically by evaluation of vertical edges without any user interaction needed.