Drop in magnitudes in the blue-yellow spectra of the barium star ζ Cap compared to the normal giant o Uma due to blanketing by heavy elements and by CH and CN. The black dots correspond to different photometric bands, as taken from Bond & Neff (1969), and the continuous lines correspond to the synthetic spectra with s-process elements increased by +1 dex (green line) and with CH added with (red line) or without (blue line) predissociation lines. While similar atmospheric parameters were used, carbon and s-process element overabundances of 0.5 dex and 1 dex were adopted, respectively.