[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?

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

Hi Laurie,

> In so far as my use of the two terms in the mistatement, "dynamic
> range" and
> "density range" tend to be used in the literature and manufacturer's specs
> synonymously as denoting the same thing (ie. the contrast range),

Yes, I know...(heavy sigh).  Marketing people tend not to really understand
the difference, and neither do most lay people...or even quite a few
technical people.  They have also been used interchangeably in photography
for many many years...unfortunately...

> Having said that,let me see if I got it by putting it into my own words.
>
>  "Density range" refers to the "contrast range" from white point to black
> point covered by the scanner and is measured in terms of 3.0 to
> 4.2 Dmax or
> D

Coooooorect!

> Whereas "bit
> depth" refers the degree of quality information or detail that can be
> obtained within the given "density range"

Bit depth is actually nothing more than the limiting factor FOR the
"detail"...but does not assure you that you will get the "detail".

> Thus, in your terms since most of the
> literature does not use any term to describe what is being measured except
> to refer to it as bit depth or x number of bits, bit depth measures the
> "dynamic range" that a device can capture within its given
> "density range,"
> as meeasured by the Dmax specification.

Again, bit depth is the limiting factor OF dynamic range, but does not
assure you that the dynamic range of the scanner is equal to the bit
depth...as in the 24 bit, w/ 12 bits of noise, example.

> Is my understanding close enough for government work or do I need
> to go back
> to the contemplation place and rethink it?

It's fine, if you understand the caveat WRT bit depth...

Regards,

Austin

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