The Scheimpflug principle states that for a plane (such as a camera lens) to remain in focus on an object, the plane of focus must be parallel to the image plane, and the plane of the lens must be angled so that it intersects the plane of focus at a specific point. This allows for a sharp focus on objects at different distances from the camera. The principle is named after Austrian optician Theodor Scheimpflug (1865–1911).
The Scheimpflug principle is a geometric rule that describes the orientation of the plane of focus in photography and optics. It states that the plane of focus is perpendicular to the plane of the image sensor and intersects with the lens axis at a specific angle, dependent on the angle of tilt of the camera relative to the subject. This allows for control of depth of field and correction of perspective distortion in photography.
The principle allows the photographer to keep planes that are not parallel to the image plane in focus by manipulating the position of the lens. In modern-day photography, the Scheimpflug principle is used in tilt-shift lenses and digital manipulation programs to achieve the same results. Figure 1 shows the alignment of three basic planes: the image plane, the lens plane, and the subject plane.
Figure 1. Principal plane for Schiempflug Photography. Image from Fil Hunter, 2006
Tilt-shift photography is a technique in which the lens of a camera is tilted and shifted in relation to the camera body to control the plane of focus and simulate a miniature effect. This creates an illusion that the captured scene is a miniature model rather than a full-scale environment. It’s commonly used in architectural, product, and landscape photography. The tilt-shift effect is created by manipulating the plane of focus, which allows the photographer to selectively blur certain areas of the image while keeping other parts sharp. This can be done by tilting the lens or shifting it either horizontally or vertically. By altering the amount of tilt and shift, the photographer can achieve different effects, such as creating a miniature world out of a full-scale environment or emphasizing certain elements in the image.
Figure 2. Tilt-shift photography of Paris. Image from Wikipedia