Dependence of f_blue on the rest-frame probed color. Top: like Fig. 6, but for B − V rest-frame color. Bottom: we compare the estimated f_blue when using the rest-frame B − V and u − r colors for 84 estimated values (10 clusters for which are available independent filter pairs probing the rest-frame B − V and u − r colors, 1 to 4 mass bins, 3 radial bins). We stress that some individual estimates of f_blue have large error bars (see Fig. 10): the 68% shortest intervals for f_blue(B − V) and f_blue(u − r) all intersect.