Upper panel: aperture statistics as a function of filter scale θ measured in the Garching model. The FFT method (squares) and the tree method (triangles) are compared for lenses at redshift z = 0.17 with m_r ≤ 22.5, stellar masses M_⋆ ≥ 10⁹   h^-1   M_⊙ and convergence field of sources at redshift z = 0.99. Error bars indicate the standard deviation of for aperture radius θ estimated across 32 fields. Lower panel: average difference signal between the FFT method and the tree method. Again the error bars show the standard deviation of the mean (field variance of difference signal divided by ).