Microlensing by a 100 M_⊙ star at two different macromodel magnifications of 15 (μ_t = 5 and μ_r = 3, left) and 60 (μ_t = 20 and μ_r = 3, right). The field of view is the same in both cases. In each case, the larger panel shows the magnification in the lens plane (critical curve) while the small panel in the bottom-right corner shows the corresponding magnification in the source plane (caustic). The small white dot inside the caustic marks the position of the source. The numbers in the larger panels indicate the magnification of each microimage and the corresponding time delays (in milliseconds) relative to the image that arrives first (marked with 0 ms). The separation between the source and the projected position of the microlens is the same in both cases. We note how at larger macromodel magnifications, both the time delays and the area enclosed by the caustic (i.e., the probability of microlensing) are larger.