>...the problem is that the only logical reference when Dmax is quoted on
>its own is against full transparency, as you state - i.e. no film, nothing
>in the way of the path betw the light source and the detector.
IMHO (and I don't really want to get into this discussion *at all*), it
would be more honest to use blank film for this test. The difference in
light transmission might be miniscule, but sensitive CCDs might also be able
to record it. Most media have a small amount of filtering properties.
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