The luminescence of Sm2+ substituting for Sr2+ or Ba2+ has been studied in SrFBr, BaFBr, BaFI and SrAlF5. The pressure induced shifts of the intra-configurational 5D0,1→7F0,1,2 observed in the MFX crystals are about three times larger than those observed in ruby, confirming thus some potential of these systems as pressure sensors. The comparison of excitation spectra in MFX shows that the position of the lowest 4f55d1 band shifts strongly to the red passing from SrFBr to BaFI. In BaFI, one observes simultaneously intra-configurational and inter-configurational emission. The non-degenerate 5D0→7F0 emission of Sm2+ in SrAlF5 confirms the presence of four crystallographic sites for Sr. Site selective spectra show clear differences for the different sites. Spectra as a function of pressure reveal different pressure shifts for the different sites.