This is my old Linhof Technika showing its extreme range of movements and a very simplified diagram of the Scheimpflug rule in action. For my simple focusing technique, knowing how far the object plane lies in relation to the lens axis is very important. Theodor Scheimpflug (1865-1911) stated that ‘ when the extended lines from the lens plane, the object plane and the film plane intersect at the same point, the entire subject plane is in focus.’ I won’t go into a detailed explanation, as much has already been written on the subject, but I hope the diagram below illustrates the concept. This is the classic illustration of the Scheimpflug rule in action. For example, by tilting the lens forward by the right distance, a photographer is able to adjust the plane of focus to run along the ground, giving a vastly increased apparent depth of field, even with the lens wide open! These cameras, with their fine mechanical controls, have the ability to move this slice of space to the left and right, up and down and most importantly tilt and swing it away from the perpendicular. Tilt shift lenses are designed to emulate the camera movements found on larger monorail and technical field cameras. A slice of focused space if you like, that also moves forward and backward, but always parallel to the film plane. The lens can move forward and backward creating a plane of sharp focus in front of it. With normal 35mm camera lenses, the axis of the lens is mounted in a fixed position at right angles to the film plane. Thanks to David Summerhayes for permission to reprint this tutorial here. It is intended to provide a more in-depth explanation of the principals involved in using this type of lens. This article is published coincident with this site’s May, 2008 report on the new Nikon 24mm PC-E lens.
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