[filmscanners] Re: IV ED dynamic range... DYNAMIC RANGE!

["David J. Littleboy" <davidjl@gol.com>]

"Austin Franklin" <darkroom@ix.netcom.com> wrote:
>>>>>>>>>>>>>>
> DENSITY RANGE is the maximum range of densities that the scanner can deal
> with / capture - using any available settings.

That is correct, and exactly what I said.

> You will in
> general have to
> modify gain and maybe other settings and do two different scans to capture
> the minimum density and the maximum density that the scanner can record,
> but the range between them is the Density Range.

And yes, correct.
<<<<<<<<<<<<<<

Really, that was a good start. But...

>>>>>>>>>>>
> DYNAMIC RANGE on the other hand, is the smaller range within the Density
> Range that the scanner can capture AT ONE TIME i.e. dynamically i.e in one
> scan.  It is the instantaneous range the scanner can handle.

Absolutely not correct.  Where on earth did you get that?  Please please
provide any credible source that says anything to the such.  The ISO spec
doesn't define dynamic range that way...nor do any of the resources I have
seen.
<<<<<<<<<<<<

Ouch. Sigh. Dynamic range:
1. The difference, in decibels, between the overload level and the minimum
acceptable signal level in a system or transducer.
<snip>
5. The difference between the maximum acceptable signal level and the
minimum acceptable signal level.
(Modern Dictionary of Electronics, 6th ed.)

Austin is, of course, right on this one. Where did that come from? A great
mystery. If we want to make things really fun, we can discuss the
differences between the dynamic range of the image on the film (we'd have to
figure out some way to define this: density range is a much more sensible
thing to talk about; in audio, the dynamic range of the source material is
easier to talk about than in film scanning), the dynamic range of the
scanner device (which is the largest dynamic range one could observe in the
output for an optimal input signal), and the dynamic range in particular
output images.

But I think most here are tired of this.

Comment: this went back and forth interminably, and I think most of that
could have been avoided by actually quoting standard definitions of the term
and working from there. It is a standard engineering term and it is not used
in a nonstandard way in this context. Sigh.

David J. Littleboy
davidjl@gol.com
Tokyo, Japan



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