We present a case study and first results of the 3 filter narrow-band delta a photometric system to detect B[e] stars in an efficient way. One filter measures the flux at 5200 A where several Fe II emission lines are located. On the basis of available spectra, we investigated the expected area in the diagnostic tool of the delta a system, the so-called normality line, where these objects are located. They are well separated from all other known non-standard stars in the corresponding Teff (color) region. The first results of our photometric survey in the Magellanic Clouds are very promising and show the high potential of delta a photometry to significantly contribute to this research field.