Rethinking Lensing and Lambda
  Strong gravitational lensing has traditionally been one of the few phenomena said to oppose a large cosmological constant; many analyses of lens statistics have given upper limits on $\Omega_\Lambda$ that are marginally inconsistent with the concordance cosmology. Those conclusions were based on models where the predicted number counts of galaxies at moderate redshifts (z~0.5-1) increased significantly with $\Omega_\Lambda$. I argue that the models should now be calibrated by counts of distant galaxies. When this is done lens statistics lose most of their sensitivity to the cosmological constant. 
Charles R. Keeton