An X-ray diagnostic apparatus, comprises an X-ray source (1), an imaging surface (6) on which the intensity distribution of the X-rays to be applied to a test object (4) is imaged, an optical imaging device for imaging an overall image (10) of the imaging surface (6) onto the entrance surface of a first image sensor (11), a device (12) for the visual display of the overall image (10), and an imaging enlargement device for the enlarged visual display of a selectable detail of the overall image. Strongly enlarged and still high-resolution detail images are generated in that the selectable detail (20) of the overall image is directed onto a second image sensor 16) which discriminates a substantially higher number of pixels relative to the unit of surface area of the overall image.