A comparison of the initial electron-density maps obtained by bromine SAD (a, b) and sulfur SAD (c, d) phasing for measurements made with lysozyme by the IMISX method at room temperature (a, c) and by the conventional method using harvested crystals in loops at 100 K (b, d). Residues Ala9–Ala32 are shown for the bromine SAD data (a, b) and residues Ala9–Ala32, Met105, Cys115 and Lys116 for the sulfur SAD data. The initial 2Fo − Fc map obtained after density modification with SHELXE was contoured at 1σ and is shown as a blue mesh. The anomalous difference maps contoured at 5σ are shown as a red mesh. Br and S atoms are labelled. The final model is shown in stick representation. The resolutions of the corresponding data are 2.0 and 1.8 Å for sulfur SAD and bromine SAD at room temperature, respectively. At 100 K, the corresponding values are 2.0 and 1.8 Å, respectively.