Images showing [Fe ii] line ratios that are sensitive to the electron density, for HH 300-IRS a)–c) and HH 72-IRS d)–f). 1.600 μm/1.644 μm, 1.664 μm/1.644 μm and 1.677 μm/1.644 μm ratios are shown for each source. Regions with no line emission have again been masked. The crosses mark the H-band continuum peak position in each image; the scale bars measure 0.8″.