Plot of the dispersion ﹩\Delta \varphi / \varphi ﹩ against median at fixed κ. Each plotting symbol is the ensemble‐average mass map of the lens, with the image positions indicated. The mass contours are in logarithmic steps of 10^0.4 (like a magnitude scale) and the third contour from the outside is always ﹩\kappa =1﹩. But note that the spatial scale is different for different lenses. Lens names on the upper right form a key. All models except J0414+053 have inversion symmetry.