Left: MegaCam r-band optical image of the Tier-1 cluster PSZ2 G077.90−26.63 (A2409) of mass at redshift z = 0.148, with convergence (i.e. surface mass density) contours overlaid. The red circle delimits R₅₀₀. Right: radial shear profile obtained for PSZ2 G077.90−26.63, showing that, besides the ability to constrain the overall mass to within 30% or so, only a modest handle on individual profile shapes is possible. The vertical lines show the outermost scale grasped by the main facilities we use for lensing, which nicely encompass the virial radius of most clusters, even at low redshift. In particular, the 0.5 − 2.5 Mpc range (radial span of the red curve) over which model fitting performs best, is well covered by our data. Grey points represent the curl component of the shear profile, which should be consistent with zero (error bars are not shown for clarity, but are the same as for the tangential component).