Last year we reported that the power of importance in self-focusing experiments is the second critical power, P₂, defined by P₂=3.77 P₁ rather than the often quoted P₁=c λ²/(32π²n₂). Here n₂ is the nonlinear refractive index, c the speed of light and λ the wavelength (both in vacuum). The factor of 3.77 is a numerical factor coming from computer calculations as discussed by Marburger [1]. We also presented a method by which we could obtain n₂ at irradiances very near to damage. In addition, we showed the experimental conditions under which self-focusing is unimportant in damage experiments. We have now extended these results so that in damage experiments where self-focusing is important we can estimate the reduced spot size within the bulk at damage and, thus, obtain the damaging electric field magnitude. This we do by observing the far field time integrated spatial irradiance distribution. We present data for SiO₂, NaCl, BK-7, and CS₂.