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[filmscanners] Re: My best scanner/film combinations




>Is this a common problem, i.e., losing the shadows, when scanning slides?  I
>have been planning on going exactly this route - shoot slides and scan when
>I want prints.
>
>-- al

Yes it is a common problem with consumer scanners, even the moderately good
ones.  The basic question is an old one, and the reason is pretty much
physics, or at least, the nature of film manufacture.

1)  A slide will record about 7 stops of brightness range in a real scene,
and EXPAND it to about 10 stops of brightness range on the film.  I am
using Ektachrome 100VS for this example, you can see this yourself if you
look at the graphs at

http://www.kodak.com/global/en/professional/support/techPubs/e163/f002_0864ac.gif

The input range in D units is around 2.0, and the output is about 3.1 - or
up to 3.5 if you want to get all the shadow detail even where the colours
are not accurate. (D of 2.0 = around 7 stops; D of 3.0 = around 10 stops; D
of 3.5 = around 12 stops).  Now a range of 3.5 is above the actual limit of
most consumer scanners, despite what the manufacturer promises, so the
simple and unappealing fact is that you will have to lose something when
you scan a full-range slide.  It is usually the shadows that get lost but
you could choose to set it up so you lose the highlights instead.

2) Negs on the other hand will record over 12 stops (D=3.7) of a real scene
and COMPRESS it to about 7 stops (D=2.0) on film.  My example is Supra -
see ...

http://www.kodak.com/cluster/global/en/professional/support/techPubs/e2519/f009_0322ac.gif

The film itself has a range of D = 2.0, obviously this is much easier for
the scanner to cope with and most consumer scanners will scan this range OK.

My observation is that my LS2000 will scan around D=2.5 range.  This means
it definitely misses some of the shadows or highlights on slides.  But it
gets all of a neg, no problem.

So to reiterate:

On a slide you are struggling to capture a film range corresponding to a
scene range of around 7 stops. Using a neg though, you can comfortably
capture the whole film range which contains an original scene range around
12 stops.

And to put it another way:

WIth slides you are losing the shadows when they get more than 5 or 6 or 7
stops darker than your highlights.

With negs you still have shadow detail even when they are 12 stops darker
than your highlights.


The price you pay for the fabulous range you get with negs is:

a) because the brightnesses have been compressed on to the neg film, when
you scan and "reconstitute" the image to look like the original scene, you
will have to "re-expand" the image.  Doing this will also expand the
visibility of grain / dye clouds / noise / film imperfections / scratches
etc so the result is a grainier, less smooth image.

b) same reason, you lose some of the subtlety and nice tonal graduation you
can get with a slide.

c) same reason, you will have to manipulate the image heavily if you want
to use ALL that range, because if you printed it straight it would look
very flat and low contrast.  This is because you simply cannot reproduce 12
stops of brightness on a screen or a piece of paper.

So my conclusion after considering all this has been to use negs for most
of my general photos, which are usually non-ideal landscapes etc. This way
I at least capture everything, and I can successfully get it from the neg
into the computer, and then make a reasonable image from it even if it is
sometimes hard work.  I don't like the noise in the skies and the other
grainy effects, but that's how it goes.

If I am photographing in controlled flat lighting, such as studio-like
setting, or landscape at the right time of day, then I prefer to use
slides, because the final image has that fine smooth tonal graduation that
you just can't get with a 35mm neg, and there is less "grain" to worry about.

You will notice that my response unsurprisingly disagrees in some respects
from Austin's!

>...why? The tonality of color negative film is better than slide film,

I don't know what "tonality" means here, but I disagree with the statement
for any interpretation I can make.  Slides scan to have more tonal
smoothness and better tonal graduation than negs.

>the
>resolution of both, for today's films, is nearly identical

Yes, the actual measured resolution, although apparent resolution on negs
is not quite as subjectively good to me, because of the noise.

>, with negative
>film having a slight edge, you have better exposure latitude with negative
>film...

agreed

>and negative film scans better.

Only from the point of view of brightness range.  Scans worse from the
point of view of noise/grain/whatever.

Just the same I use negs most of the time, but a lot of this is bec my
subjects and my skill combine to mean that I rarely have the lighting flat
enough for a slide that I can scan without loss.

Julian

...and I didn't venture into the Tomb of the Forbidden Topic even once!

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