Re: Black and white negative scanning
Re: Black and white negative scanning
- Subject: Re: Black and white negative scanning
- From: Jan-Willem Rossee <email@hidden>
- Date: Thu, 15 Nov 2007 10:19:07 +0100
This is actually sort of semi-OT but it relates to the context of
this discussion and is a matter of particular interest . The term
dynamic range is very often "glossed over" by the marketing
department or even stated misleadingly as maximum optical density.
The optical density evaluation is nice to know but doesn't say
anything about the effective performance of the scanner because in
photography we are dealing with continous tone photographic media.
The "dynamic range" specified by the manufacturers is usually the
potential bitdepth from the A/D-converter, which is not the correct
definition of dynamic range. It is the range between the darkest and
brightest spots in the original and should be measured according to
ISO 21550:2004 - methods for measuring and reporting the dynamic
range of electronic scanners for continuous tone photographic media.
Please don't get me wrong, a dmax of 4.0 is great, but only half the
truth and no good when the effective dynamic range is just above 3.
Only if the effective dynamic range of the scanner is equal to 4.0 or
more the scanner will capture the full dynamic range of the original.
Image Engineering, Dietmar Wueller evaluated the dynamic ranges with
some popular scanners based on ISO 21550 --> http://
digitalkamera.image-engineering.de/index.php/Publications
Dynamic range IS a critical parameter especially when scanning B&W
negs since they are indeed capable of exceeding most scanners dynamic
ranges.
Best,
Jan-Willem Rossée
A dynamic range of 5.0? You're talking Status T densitometry? I
find that hard to believe. That means the highlights would be
blacker than the DMax of a transparency.
Ah ha - I thought someone would step up and say that! T grain films
in our developer were constantly pushing the ~3.7 range of
traditional scanners. I once had a B&W neg (I forget what it was)
that I slapped on the densitometer and was blown away that it was
almost 5.0. And yes it was clearly darker than common transparency
DMax. Like I'm sure you do, I saw all kinds of crazy originals when I
was a drum scan operator.
And while the common perception of liquid mounting is that it is a
hassle - I personally find it a wonderful process that *saves* time
that often leaves originals in a cleaner condition than they were
prior.
Scott Martin
www.on-sight.com
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden