BB fits for SN 2008if at 72 days after explosion. Different linestyles and colours correspond to different set of bands used for the fitting process. The blue solid line is the optimal model since data affected by line blanketing (u, B, and g bands) are removed from the fit. The best-fitting BB temperatures (T_BB) are indicated in the legend. An optical spectrum taken at 70 days after explosion is presented in grey. It shows that H_α line profile produces an increment of the r-band flux above the BB model.