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

["Kapetanakis, Constantine" <KAPETAC@polaroid.com>]

You are right. The max optical density of our ss120 scanner as an example is
about 3.6~3.7. We measure this we a slide we made in house on Velvia film.
Each step on the gray scale is .1 density units different and we look at the
point of clipping as the maximum density.
 However, when Nikon starts advertising theoretical maximums of 4.2 ( 14
bits) then we have to start advertising the same way.


-----Original Message-----
From: Austin Franklin [mailto:darkroom@ix.netcom.com]
Sent: Thursday, August 08, 2002 9:38 AM
To: KAPETAC@polaroid.com
Subject: [filmscanners] RE: IV ED dynamic range... DYNAMIC RANGE!


Constantine,

Typically, for some reason, marketing people have been confusing the term
dynamic range with density range, and saying a scanner has a dynamic range
of 4.0 (or whatever), when they mean density range.  That is where a lot of
this misinformation on what dynamic range really "means" has proliferated,
at least as it applies to scanners.

Typically, Density Range is measured in Density units, like 4D...and what
that means is the scanner can scan a brightness range of 1 to 10,000...as
the 4 means 10**4.  It's a ratio...and the ratio is "to 1"...so the scanner
can basically scan a brightness range of 10,000:1.

Austin

> Just as a point of reference. For all Polaroid scanners the dyanamic range
> and maximum density or density range are the same.

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