[filmscanners] Re: Scanning negs vs. slides

["Julian Robinson" <jrobinso@pcug.org.au>]

I have a question that popped up while I was taking a close look at Fuji
data sheets to confirm my prejudices.

But first, email lists must be the absolute worst way of transferring
information when emotion gets into it!!    Just slow enough and distant
enough so that you can't get sufficient feedback for correction and shades
of meaning (as you can if you try it face to face), but fast enough so that
the emotion doesn't cool between goes (as it does in snail mail).

My question:  The business of density ranges and recorded exposure range
is, I thought, not a mystery at all if you look at the transfer
curves.  There you can directly see what exposure range will go on the film
and what density range is recorded on the film as a result.  So far so good.

Now I always assumed that slides were geared up so that the density range
on the slide was roughly the same as the original exposure range, so that
scenes were recorded and viewed at about the original dynamic range.  But
this is not so according to Fuji's curves, in fact slides are recorded with
a density range around 10 times that of the original scene - i.e.
significantly more contrast.  Now 10 times when log-ified is not a huge
amount but still significant, so why is this done?

Example - Provia 100 will record a scene exposure range of about log 1.8 (6
stops) onto a film density range about log 2.8 (9 stops). Why?

I can only assume that people find slides more pleasing when the contrast
is enhanced, but why is this so universal, or have I missed something?

Julian

(note re negs, here a scene exposure range of about 11 stops is recorded on
the neg as a density range of about 6 stops, so we can see how much the
dynamic range is compressed i.e. 5 stops or 30:1.  This is why I wonder
about the grain being re-expanded when contrast is restored).

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