From exact non-Born-Oppenheimer simulations of the dissociative-ionization dynamics of H-2(+) in an intense (I > 10(15) W/cm(2)), ultrashort (t(p) < 5 fs) = 800 nm laser pulse, one can measure the time evolution of the probability distribution \psi (R, t)\(2) of the initial proton wave packet. It is shown that best imaging is obtained for ultrashort pulses (t(p) < 3 fs) at 4 x 10(15) W/cm(2) or much shorter wavelengths, less than or equal to 30 nm. The relevance of this imaging criterion is discussed in relation to current laser Coulomb explosion imaging of proton transfer in large molecules.