Yaw-free
Yaw-free Cameras
"Yaw" is defined as the sideways tipping of a standard when swung round its vertical axis during a sharpness adjustment of an oblique plane. Although this "minor" error can easily be corrected by changing the camera position to bring the verticals back to vertical, the sharpness adjustment already made then needs repeating. Focusing turns into a time consuming process of trial and error, until the photographer finally accepts a compromise. Since 1972 Sinar has therefore been designing its cameras for absolutely yaw-free.
Yaw-free movements are relevant in practice when an adjustable camera has to preserve the perspective, after the vertical receding lines have been set, and a swing around the vertical axis is still necessary.
Whether a camera yaws during this operation or not depends on its design. The sequence of joints has to ensure that when the standard is swung, the joint mechanism for the swing round the vertical axis simultaneously turns.
For sharpness plane adjustment this type of design has the advantage that Scheimpflug´s law is completely satisfied, that is a line through subject, lens and image planes coincides, while a camera which yaws is restricted to a point of intersection of the three planes. As a result, some complicated movements are not nearly as effective, and take much longer.
Whether a camera yaws or not depends on the sequence of the joints. If the joint for tilting about the horizontal axis (1) comes first in the standard block, the camera design is yaw-free.
If however the joint for swinging round the vertical axis (2) is located ahead of the joint for tilting round the horizontal axis (1), the camera will be subject to yaw.
With a yaw-free camera combined swings and tilts round the horizontal and vertical axis can be set quickly and easily.
Cameras that yaw during swinging require continuous and time-consuming correction of the verticals and alteration of the camera position.