An apparatus for obtaining a long length x-ray image of a subject has a first x-ray detector, a second x-ray detector, and an x-ray source having an exposure directing apparatus that is actuable to direct exposure from the x-ray source towards at least a first imaging position during a first interval and a second imaging position during a second interval, with an overlap along a boundary between the at least first and second imaging positions. An x-ray detector holder has a detector translation apparatus that is actuable to translate at least one of the first and second x-ray detectors to an interim position for one of the first and second intervals and to either the first or the second imaging position for the other of the first and second intervals. A host controller is programmed to provide instructions for movement of the x-ray detector holder and exposure directing apparatus.