  We compute the weak lensing convergence power spectrum,
$C^{\kappa\kappa}(\theta)$, in a dust-filled universe using fully non-linear
general relativistic simulations. The spectrum is then compared to more
standard, approximate calculations by computing the Bardeen (Newtonian)
potentials in linearized gravity and utilizing the Born approximation. We find
corrections to the angular power spectrum amplitude of order ten percent at
very large angular scales, $\ell ~ 2-3$, and percent-level corrections at
intermediate angular scales of $\ell ~ 20-30$.
