Transmission (in %) of an off-axis source as a function of the distance to the star (in units of λ/D), for a) and d) apertures with no spiders; b) and e) apertures with 0.5% thick spiders; and c) and f) apertures with 1% thick spiders. Figures a), b), and c) correspond to a charge 2 VC; and figures d), e), and f) correspond to a charge 4 VC. In each case, the transmission is given for the five central obscurations: 10, 15, 20, 25, and 30% (from top to bottom). The red dots indicate the IWA of each coronagraph.