Magnification in the source plane of a single microlens near a macro-CC where μ_m = 1000. The darkest blue indicates a lower magnification, while the whites show where the magnification diverges (i.e. the micro-caustics). Left: single microlens on the positive parity side of the CC. The caustics have the familiar diamond shape. Right: same, but in the negative parity region, crossing the macro-CC. Now the shape of the micro-caustics is broken into two distorted triangles with a demagnification area in between, but increasing the maximum achievable magnification at the tips of these triangles. Outside the caustics, the average magnification is that of the macro model μ_m. The vertical direction has been scaled down a factor ~10 for better visualisation. The probability of magnification for both examples is shown in Fig. 2.