An X-ray device has an X-ray detector allocated to an X-ray tube assembly and configured as a flat panel detector, in which charges, accumulated over an integration period, of individual detector pixels are read out in a readout period following on from the integration period. In order to acquire the X-ray images, a trigger signal is captured, and if a trigger condition evaluating the trigger signal is satisfied, the acquisition of one of the X-ray images takes place using an integration period with a predetermined default length that is the same for all X-ray images. During the acquisition of the time series, in addition to the trigger condition, a readout condition that describes the anticipated imminence of the satisfaction of the trigger condition within a default period that is greater than or equal to the predetermined default length and evaluates the trigger signal is also monitored.
