[filmscanners] RE: Scanning negs vs. slides

["Austin Franklin" <darkroom@ix.netcom.com>]

> > Ask Kodak.
>
> I'm asking you, not Kodak.  You made the assertion.

Anthony,

WHAT assertion?  You have bad snipping habits.  Anyway, whether I can
explain something (what ever it may be) to you or not, doesn't mean it does
or doesn't exist.

> > The reasons I gave, that you snipped ARE
> > the right reasons.
>
> Because you say so?

Because they're well founded.

> > Higher contrast means LESS tones, if they are
> > both over the same density range.
>
> Contrast and density range are inextricably linked.

ABSOLUTELY not true.  You can have film that has a very wide density range,
yet has very low contrast, simply because there are more tones available.
Then comes litho film, which has very high contrast, but very limited
tonality.  Of course, differences of the same density yield the same
contrast, but if you were to image a step wedge on both, the first would
have less contrast between tones.

> The number of intermediate
> tones that can
> be resolved between two arbitrary densities is relatively constant across
> negative and transparency films.

Absolutely not true either.  The number of tones is based on noise, and
noise is very dependant on development, as well as exposure.

> Thus, since slide films have more rapid
> changes in density over a small range of exposure values, they record more
> intermediate tones over this range than do negative films,
> which show a
> slower change in density over a broader range of exposures.

If something has "more rapid changes in density" in the same density it will
have less tone.  That's why something that has "less rapid changes in
density", though it has the same density range, will appear to have less
contrast, since the intermediate tones are filled in.  Your example is the
exact opposite of your claim of positives having "more tones"...

> > Density range is merely the overall range
> > of density.
>
> So density range = density range?  What does that tell me?

The range of density.

> Let me try:  Density range is the difference or ratio between
> clear film and
> the darkest color of the emulsion.

No, it is not a ratio.  It is merely a difference.

> > Dynamic range basically is how many discernable
> > tones there are within that range.
>
> Dynamic range has multiple definitions, but yours is not among
> them.

I gave an equation, THE equation, for dynamic range.  There are no others.
As I said, you don't understand what it is.  Dynamic range is very misused
in the imaging industry, for some reason, but not misused in audio and
mechanical engineering.

> It can
> refer to the entire range of magnitudes (of light intensity,
> etc.) that can
> be usefully recorded,

That's density range, not dynamic range.  The two are not interchangeable.

> but it can also refer to the entire range of
> magnitudes that can be accurately displayed or printed.

What the heck is a "range of magnitudes"???

Austin

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