Magnification probability approximation for an inverse ray-shooting simulation of an isolated microlens near a macro-CC. Each curve represents a different microlens mass. For a fixed pixel size (2 nas), the maximum magnification we can measure increases with he mass of the microlens. The dashed lines represents the μ⁻² power-law that govern the magnification probability at high magnification factor in this regime. The amplitude of this power-law increases cuadratically as seen in Sec. (4).