  Weak lensing surveys are emerging as an important tool for the construction
of "mass selected" clusters of galaxies. We evaluate both the efficiency and
completeness of a weak lensing selection by combining a dense, complete
redshift survey, the Smithsonian Hectospec Lensing Survey (SHELS), with a weak
lensing map from the Deep Lens Survey (DLS). SHELS includes 11,692 redshifts
for galaxies with R < 20.6 in the four square degree DLS field; the survey is a
solid basis for identifying massive clusters of galaxies with redshift z <
0.55. The range of sensitivity of the redshift survey is similar to the range
for the DLS convergence map. Only four the twelve convergence peaks with
signal-to-noise > 3.5 correspond to clusters of galaxies with M > 1.7 x 10^14
solar masses. Four of the eight massive clusters in SHELS are detected in the
weak lensing map yielding a completeness of roughly 50%. We examine the seven
known extended cluster x-ray sources in the DLS field: three can be detected in
the weak lensing map, three should not be detected without boosting from
superposed large-scale structure, and one is mysteriously undetected even
though its optical properties suggest that it should produce a detectable
lensing signal. Taken together, these results underscore the need for more
extensive comparisons among different methods of massive cluster
identification.
