In electron diffraction measurement, if we are measuring the HOLZ rings at large scattering angles (e.g. ≥10°), then we need to use known standard samples to correct the distortion in reciprocal space. At such high angles, the electrons travel close to the polepiece and thus the lens imperfection causes the diffraction distortion. However, aberration correction, e.g. C_s correction, can minimize such distortion.