RE: Black and white negative scanning
RE: Black and white negative scanning
- Subject: RE: Black and white negative scanning
- From: "Bertho Boman" <email@hidden>
- Date: Thu, 15 Nov 2007 05:29:21 -0500
I did similar measurements on digital cameras using different lens types and
got surprisingly low dynamic range and posted it on a couple of user groups.
I got very little feedback which surprised me since it is of limited use
talking about lots of bit depth if in real life they are not useful.
Further, I never see this mention on camera and lens evaluations in
magazines and that is surprising too since there is a big difference between
different lenses and camera designs.
The significant feedback from the posts actually came from a camera
manufacturer, not users.
http://www.vinland.com/Contrast.html
Bertho
> -----Original Message-----
> From: Jan-Willem Rossee Sent: Thursday, November 15, 2007 04:19
> 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
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