Typical 3DXRD data from a coarse-grained undeformed polycrystal. The sample is an annealed aluminium polycrystal with grains of average size 70 µm. The X-ray energy was 55 keV. The left and middle images are `near-field' exposures with two screens (see Fig. 1) at distances from the sample of L = 7 mm and L = 17 mm, respectively. The elongated central holes in the two screens are clearly visible. On the right is a corresponding `far-field' image made with a low-resolution detector at L = 190 mm. In the latter case the diffraction spots are positioned on Debye–Scherrer rings.