The TS-E 90 mm f/2.8 provides three degrees of freedom, allowing ±8° tilt with respect to the image plane and ±11 mm shift with respect to the center of the image area;[1] the movements can be rotated ±90° about the lens axis, though not independently.
Shifting allows adjusting the position of the subject in the image area without moving the camera back; it is often used to avoid convergence of parallel lines, such as when photographing a tall building.
Tilting the lens relies on the Scheimpflug principle to rotate the plane of focus away from parallel to the image plane; this can be used either to have all parts of an inclined subject sharply rendered, or to restrict sharpness to a small part of a scene.
The lens is supplied with these functions at 90° to each other (e.g., providing tilt and lateral shift); they can be changed to work in the same directions (e.g., providing tilt and rise/fall) by removing four screws, rotating the front of the lens 90°, and reinstalling the screws.
Main difference compare to the TS-E 90 mm f/2.8 is the Macro capability and the change to the L line.