Perspective correction lens

Tilt–shift photography is the use of camera movements on small- and medium-format cameras, and sometimes specifically refers to the use of tilt for selective focus, often for simulating a miniature scene.

Sometimes the term is used when the large depth of field is simulated with digital post-processing; the name may derive from a perspective control lens (or tilt–shift lens) normally required when the effect is produced optically.

"Tilt–shift" encompasses two different types of movements: rotation of the lens plane relative to the image plane, called tilt, and movement of the lens parallel to the image plane, called shift.

Tilt is used to control the orientation of the plane of focus (PoF), and hence the part of an image that appears sharp; it makes use of the Scheimpflug principle. Shift is used to adjust the position of the subject in the image area without moving the camera back; this is often helpful in avoiding the convergence of parallel lines, as when photographing tall buildings.

Movements have been available on view cameras since the early days of photography; they have been available on smaller-format cameras since the early 1960s, usually by means of special lenses or adapters. Nikon introduced a lens providing shift movements for their 35 mm SLR cameras in 1962, and Canon introduced a lens that provided both tilt and shift movements in 1973; many other manufacturers soon followed suit. Canon currently offers four lenses that provide both movements while Nikon offers three. Such lenses are frequently used in architectural photography to control perspective, and in landscape photography to get an entire scene sharp.

Some photographers have popularized the use of tilt for selective focus in applications such as portrait photography. The selective focus that can be achieved by tilting the plane of focus is often compelling because the effect is different from that to which many viewers have become accustomed. Ben Thomas, Walter Iooss Jr. of Sports Illustrated, Vincent Laforet and many other photographers have used this technique.

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Wikipedia