An X-ray apparatus is provided with a filter (12) for limiting the dynamic range of an X-ray image formed on an X-ray detector (4) by exposure of an object (3), for example a patient to be examined, to X-rays (2). The filter (12) has filter elements (13) including one or more capillary tubes (13), one end of which communicates with a reservoir with an X-ray absorbing liquid. The adhesion of the X-ray absorbing liquid to the inner side of the capillary tubes can be adjusted by means of an electric voltage applied to an electrically conductive layer provided on the inner side of the capillary tubes (13). The degree of filling of the capillary tubes (13) with the X-ray absorbing liquid is adjusted by way of the electric voltage value. The X-ray absorption profile is adjusted within a very short period of time, for example within one second, by adjustment of the electric voltages applied to the capillary tubes (13).