A Simple Instrument for Measuring Image Steadiness in 16-mm Motion-Picture Cameras

Abstract

Frame-to-frame image registration errors in a 16-mm cine camera can be measured directly by the moiré fringes formed by a double exposure of a Fresnel zone pattern target. A simple instrument incorporating a target and lens that attaches directly to the camera under test was designed and built. If the Fresnel zone pattern images are displaced with respect to one another, linear image registration errors are converted into angular motion of the fringes; it then becomes possible to separately analyze in-track and cross-track errors. The necessary displacement between exposures is provided by the rotation of an off-center target. The test film can be projected with a conventional projector and an estimate of the registration errors obtained, or the film can be analyzed with a low-power microscope or single-frame analytical projector. It will be most suitable for testing cameras in research, manufacturing, and repair.