  The CNOC redshift survey of galaxy clusters measures Omega_M from Omega_e(z)=
M/L x j/\rho_c which can be applied on a cluster-by-cluster basis. The
mass-to-light ratios, M/L, are estimated from rich galaxy clusters, corrected
to the field population over the 0.18 to 0.55 redshift range. Since the
luminosity density depends on cosmological volumes, the resulting Omega_e(z)
has a strong dependence on cosmology which allows us to place the results in
the Omega_M-Omega_Lambda plane. The resulting Omega_M declines if
Omega_Lambda>0 and we find that Omega_Lambda<1.5.
