  Motivated by the recent results for DIS off nuclei from the HERMES experiment
we have performed a systematic study of shadowing for transverse and
longitudinal photons. We found that the coherence length which controls the
onset of nuclear shadowing at small x_{Bj} is much longer for longitudinal than
transverse photons, and is much shorter for shadowing of gluons. The light-cone
Green function approach we apply properly treats shadowing in the transition
region x_{Bj}>0.01. It also incorporates the nonperturbative effects and is
legitimate at small Q^2. We calculate nuclear shadowing and compare with data
from the HERMES and NMC experiments. Although we expect different nuclear
shadowing for longitudinal and transverse photons, numerically it cannot
explain the strong effect observed by the HERMES collaboration.
