Wednesday, September 12, 2007

Tilt-Shift Photography

Doing something as simple as tilting the lens so it is no longer perpendicular to the film makes a very narrow band of focus that makes the picture look like a miniature.

If you’re curious, here’s how tilt-shift photography works. A tilt-shift lens allows the photographer very exacting control over the depth-of-field in an image, much more than any regular lens could provide. Focus can be restricted to a single, narrow band, with everything else rapidly blurring away. This distorts the appearance and makes the eye think that distances are a lot smaller than they typically are. When applied to a large scene like a city or a museum, everything appears miniature.

Edit:A Reddit user gives this additional explanation for the effect.

It’s because tilting the lens with respect to the film/sensor plane changes the perspective in the image: you can make lines that otherwise would converge, showing perspective, instead remain parallel or even diverge. It’s not just the depth of field that matters to your brain. Hence the photoshop demonstration isn’t all that effective; the perspective of the objects in the image would also have had to change.

UPDATE: More on Tilt-shift photography.

Wikipedia on Tilt-shift photography
Tilt-shift photography refers to the use of camera movements on small- and medium format cameras, often tilting the lens relative to the image plane to achieve a very shallow depth of field. The technique relies on the Scheimpflug principle and usually requires the use of special lenses. “Tilt-shift” actually encompasses two different types of movements: rotation of the lens, 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. Shift is used to control perspective, usually involving the convergence of parallel lines.



On a regular camera, the image plane (containing the film or image sensor), lens plane, and object plane are parallel, and objects in sharp focus are all at the same distance from the camera. When the lens plane is tilted relative to the image plane, the PoF is at an angle to the image plane, and objects at different distances from the camera can all be sharply focused if they lie on a straight line. With a tilted lens, the image plane, lens plane, and PoF intersect at a common line;[3] this behavior has become known as the Scheimpflug principle. When the PoF coincides with an essentially flat subject, the entire subject is sharp; in applications such as landscape photography, getting everything sharp is often the objective. But the PoF can also be oriented so that only a small part of it passes through the subject, producing a very shallow region of sharpness, and the effect is quite different from that obtained simply by using a large aperture with a regular camera.

View camera users usually distinguish between rotating the lens about a horizontal axis (tilt), and rotation about a vertical axis (swing); small- and medium-format camera users often refer to either rotation as “tilt”.



In a subject plane parallel to the image plane, parallel lines in the subject remain parallel in the image. If the image plane is not parallel to the subject, as when pointing a camera up to photograph a tall building, parallel lines converge, and the result sometimes appears unnatural, such as a building that appears to be leaning backwards. Shift is a movement of the lens parallel to the image plane that allows the line of sight to be changed while keeping the image plane parallel to the subject; it can be used to photograph a tall building while keeping the sides of the building parallel. The lens can also be shifted in the opposite direction to accentuate the convergence for artistic effect.

Again, view camera users usually distinguish between vertical movements (rise and fall) and lateral movements (shift or cross), while small- and medium-format users often refer to both types of movements as “shift”.

Tilt-shift photography links

1 comment:

Anonymous said...

Not accurate. The Reddit user is being quoted when they don't know how a tilt-shift lens works. Tilting the lens doesn't change the perspective, shifting does.

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