An X-ray optical configuration (1), comprising a position for an X-ray source (2), a position for a sample (3), a first focusing element (4) for directing X-ray radiation from the position of the X-ray source (2) via an intermediate focus (5) onto the position of the sample (3), and an X-ray detector (6) that can be moved on a circular arc (7) of radius R around the position of the sample (3), is characterized in that the configuration also comprises a second focusing element (8) for directing part of the X-ray radiation emanating from the intermediate focus (5) onto the position of the sample (3), and an aperture system (9) for selecting between illumination of the position of the sample (3) exclusively and directly from the intermediate focus (5) (=first optical path (10′)), or exclusively via the second focusing element (8) (=second optical path (10″)). The configuration facilitates changing between reflection geometry and transmission geometry, in particular, wherein modification and adjustment devices are minimized or unnecessary.