Synthetic images showing the intensities of important emission lines from various ionization stages of oxygen around very massive stars with metallicities of 0.05 Z_⊙ and 1.0 Z_⊙. Lower metallicity means lower densities of the metal ions in the gas, but the corresponding reduction of the optical emission lines is partly compensated by the higher temperatures and the resulting higher rate coefficients for collisional excitation. The values are shown using a logarithmic color scale because the emission line strengths vary strongly between the different models.