tell a friend about this article
 

	Introduction
»	Shift & tilt basics
	A powerful lens
	Handling & tests
	More tests...
	Resolving power
	Field tests
	In the field & Conclusions

Shift in a lens, means a displacement of it, maintaining its optical plane parallel to that of the film or digital sensor; it moves the lens axis away from that of the image frame; hence its name, shifting. It is useful to change the relative position of the subject(s), without moving the camera, and to correct perspectives.

Lens shift (Illustrations courtesy of Nikon Spain / Finicon, S.A.

Tilt changes the incident angle of the image on the film or digital sensor, by rotating the lens. It has an effect on the depth of field, extending the focused plane, not parallel to the film or sensor anymore.

According to the Scheimpflug principle, a sharp image occurs where the focusing or subject plane, the lens optical plane and that of the film/sensor intersect. It is easy to comprehend the importance of this principle remembering that, at macro photography under ambient light, one seems to never have enough depth of field and light looks like seldom sufficient for closing down the lens while maintaining reasonable shutter speeds. So with this capability, photographers can now focus on butterflies without having to be parallel to their bodies or closing the lens down to its smallest aperture.

Both shift and tilt can be performed in all directions and be combined.

Obviously the lens requires to be of a special design, and not just mechanically. The circle of the projected image must be much bigger than that to normally cover the film or digital sensor format, since the corners or margins will be used, where light fall and optical aberrations are more noticeable. This explains why these lenses need to be and are ultra-corrected.