Extinction map of Fig. 1 (red contours) overlaid on the 870 μm continuum emission map of Cha III (black contours). The contour levels of the extinction map start at 3 mag and increase by steps of 1.5 mag. The thicker red contours correspond to A_V = 4.5 and 7.5 mag. The contour levels of the 870 μm map are the same as in Fig. 2, plus a dotted blue contour at  −a. The dotted line delimits the field mapped at 870 μm. The field of view of LABOCA and the angular resolution of the extinction map are shown in the upper right corner.