Convergence–shear diagrams for e = 0 NFW lenses with five values of κ_s as marked along the right axis. The conversion between different values of κ_s is obtained simply by scaling the plot from the origin by the target/original κ_s value ratio. The three dashed orange lines connect points on the different curves corresponding to radius a = 1, to radius a = 0.1, and to radius a = 0.01.