Tilt and shift lens
Shift movements enable the photographer to shift the location of the lens’s imaging circle relative to the digital camera sensor. This means that the lens’s center of perspective no longer corresponds the the image’s center of perspective, and produces an effect similar to only using a crop from the side of a correspondingly wider angle lens.
Tilt movements enable the photographer to tilt the plane of sharpest focus so that it no longer lies perpendicular to the lens axis. This produces a wedge-shaped depth of field whose width increases further from the camera. The tilt effect therefore does not necessarily increase depth of field—it just allows the photographer to customize its location to better suit their subject matter.
What is your view about this type of lens?