(a) Schematic of the setup: (1) Si attenuation foils, (2) silts S1, (3) slits S2, (4) focusing optics (KB mirrors), (5) pinhole, (6) focal region with the resolution chart sample, (7) semi-transparent central stop (STCS), (8) photon-counting detector. (b) Diffraction pattern taken with the STCS and 166.8 µm Si attenuation foils (1). (c), (d) Inner part from (b) without and with, respectively, rescaling with respect to the area attenuated by the STCS (7). (e) Diffraction pattern taken without an STCS but with 444.8 µm Si attenuation foils (1). (f), (g) Line profiles through the rescaled diffraction pattern shown in (d) [indicated by black dashed lines in (d)] in the horizontal and vertical direction (solid black lines), respectively. Up-scaled line profiles (scaling factor = 8.3×101/1.3 = 63.85) through a diffraction pattern taken without the STCS are shown as solid red lines. The STCS region is indicated by black dashed lines in (f) and (g). Scale bars denote 50 µm−1 and 10 µm−1 in (b), (e) and (c), (d), respectively. The exposure time is 1 s in (b) and (e). The colour bar in (e) is the same as in (b).