Hα images of 20 nearby Southern galaxies were obtained using narrow interferometric filters. Positions, fluxes and diameters of the objects were obtained from these frames. A study of the completeness of the sample is made and after a proper calibration, the absolute fluxes and the Hα luminosity function were obtained for each galaxy. Two galaxies in the sample (NGC 1672, NGC 5861) show profiles of type II luminosity function while NGC 6221 shows extended Hα emission.