  Photometric redshifts can be routinely obtained to accuracies of better than
0.1 in Delta(z)/(1+z). However, the issue of dust extinction is one that has
still not been well quantified. In this paper the success of two
template-fitting photometric redshift codes (IMPZ and HYPERZ) at reliably
returning Av in addition to redshift is explored. New data on the CNOC2
spectroscopic sample of 0.2<z<0.7 galaxies are presented. These data allow us
to estimate Av values from the observed Balmer decrements. We also investigate
whether the empirical value of gamma=0.44, the ratio between gas- and star-
derived extinction, as determined by Calzetti (2001), is necessarily the best
value for this sample.
  When comparing the two codes to the Balmer-derived Av, a correlation between
the photometrically derived Av, Phot-Av, and the Balmer-Av is found. The
correlation is improved when the empirical value of gamma=0.44 is allowed to
vary. From least-squares-fitting the minimum in the reduced chi^2 distribution
is found for gamma~0.25 +/- 0.2. For the sample of galaxies here, the factor of
two difference in covering factor implied by the Calzetti ratio is found to be
plausible. The CNOC2 galaxies with detected Balmer lines have some preference
for an increased covering factor difference, which would perhaps imply they are
undergoing more rapid, `bursty' star formation than the galaxies Calzetti used
in her derivation.
