The optical constants of a range of semiconductors, from wide bandgap materials (GaN and AlN) over mid-bandgap materials (GaAs and InP) to narrow bandgap materials (InSb and HgTe) have been modeled over a wide spectral range. We compare several models in terms of accuracy, intricacy of model equations and the number of adjustable parameters. It has been found that a modified Adachi's model with adjustable broadening function obtains the best agreement with the experimental data for all investigated materials. An adjustable broadening function enables greater flexibility of the model, since no broadening mechanism is specified a priori and inhomogeneous broadening can be taken into account.