  The spectroscopic factor arises from short-range effects in the nuclear wave
function. On the other hand, cross sections for external capture reactions,
such as $^7$Be$(p,\gamma)^8$B at low energies, depend primarily on the
asymptotic normalization of the bound-state wave function -- a long-range
property. We investigate the relationship between potential models and the full
many-body problem to illustrate how microscopic substructure effects arise
naturally in the relevant transition matrix element and can be (in part)
accounted for by a spectroscopic factor.
