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 \simeq - 1.0 , with no marked faint-end upturn to our limit of M _ { R } \simeq - 15.0 , and only a mild radial gradient .
In each case , the radial profile of the M / L ratio peaks at intermediate radius , \simeq 0.2 r _ { vir } , at a level of 300 - 500 ( M / L _ { R } ) _ { \odot } , and then falls steadily towards \sim 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 .