Screened precession method for area detectors

A method is presented in which the features of a Buerger-type mechanical precession camera can be simulated using an electronic area detector and a three-circle automated goniostat. The resulting display as viewed on a video monitor is very much like a conventional precession photograph. The detector is stationary which causes a distortion that is negligible for precession angles less than 10 degrees. The virtue of this new method is that a precession image may be collected very fast and the intensities of the reflections when displayed are already digitized. The usefulness of these features is presented through two familiar tasks: the determination of a new protein crystal space group and the evaluation of a heavy-atom derivative.