  Weak lensing work can be badly compromised by unlensed foreground and cluster
members which dilute the true lensing signal. We show how the lensing amplitude
in multi-colour space can be harnessed to securely separate cluster members
from the foreground and background populations for three massive clusters,
A1703 (z=0.258), A370 (z=0.375) and RXJ1347-11 (z=0.451) imaged with Subaru.
The luminosity functions of these clusters when corrected for dilution, show
similar faint-end slopes, \alpha ~= -1.0, with no marked faint-end upturn to
our limit of M_R ~= -15.0, and only a mild radial gradient. In each case, the
radial profile of the M/L ratio peaks at intermediate radius, ~=0.2r_{vir}, at
a level of 300-500(M/L_R)_\odot, and then falls steadily towards
~100(M/L_R)_{\odot} at the virial radius, similar to the mean field level. This
behaviour is likely due to the relative paucity of central late-type galaxies,
whereas for the E/S0-sequence only a mild radial decline in M/L is found for
each cluster. We discuss this behaviour in the context of detailed simulations
where predictions for tidal stripping may now be tested accurately with
observations.
