Lyα absorption along a sight line near a z = 3 L_νLL = 10³²   erg   Hz^-1   s^-1 QSO simulated with photon numbers N_p,QSO = 1  ×  10⁸ (solid line), 1  ×  10⁹ (dashed line), 2  ×  10⁹ (dotted line), and 4  ×  10⁹ (dash dotted line). The wavelength is in Ångström and no noise is added to the spectra for better visibility. The lower panel shows the relative deviation from the highest resolution run.