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[filmscanners] A partial fix for Minolta scanners?


  • To: lexa@lexa.ru
  • Subject: [filmscanners] A partial fix for Minolta scanners?
  • From: "Arthur Entlich" <artistic-1@shaw.ca>
  • Date: Fri, 18 Oct 2002 02:22:59 -0700
  • Unsubscribe: mailto:listserver@halftone.co.uk

As many of you know, I own a Minolta Dual Scan II.  Although I
recommended this scanner  due to its lower cost and fairly good quality
scans, I was unhappy with three aspects.

1) Quality control problems where one or more CCDs in one or more
channels would be miscalibrated causing lines to appear across the scan

2) Something within the optical path which caused the scanner to produce
scans which had exaggerated dust, dirt, scratches and grain, dissimilar
from other scanners offering a cold cathode diffused light source.

3) occasional and intermittent mis-calibration causing a pink section
down the center of negative scans.

The other problems with this scanner are: slow USB connection and 12 bit
A/D converter which allows for some shadow noise and problems getting
detail out of the deep shadows.  These two issues have been addressed in
the Minolta Elite II (with Firewire and 16 bit A/D converter) and the
new Minolta Dual Scan III with new software and  16 bit A/D converter.

For people who dodged the QC bullet and got one without "lazy sensor"
lines, and for those who either do not have the calibration problems, or
find the transient nature not much of an issue, I have some potential
good news.

As I have mentioned before, The Elite II and Pro medium format scanner
have both had a software and firmware version upgrade which helps to
take care so some of these elements.  However, the revision did not fix
some of the optical problems, and no upgrade was provided for the Dual
Scan II.

Issue number (2) has been one of some conjecture.  WHy is it that a
diffuse light source scanner is capturing so much surfaced  defect?  I
suggested that it may be a matter of overfocusing the scan and
surpassing the Nyquist limitations for this scanner, therefore
introducing more noise and surface defects than it should.  I suggested
a slight defocusing might help, and a control to allow for this would be
nice in software.

Some of you may know that Bo Wrangborg, owner of the Minolta Pro list,
has been battling with Minolta for some time trying to get them to
resolve this problem.  I got involved in some manners because of my
ownership of the Dual Scan II and trying to get Minolta to acknowledge
these difficulties.

Recently Bo and a gent from Holland got together to see what could be
done to resolve this problem with excessive surface defect and noise.
It would appear that they have come up with an answer.  As we already
know, from Nikon's use of LED lighting, collimated light sources cause
considerable increase in visibility of dust, grain, dirt, scratches and
grain.  What Bo and the other person did was to try diffusing the light
source further by using some diffusion materials between the light
source and the film.  The results are quite considerable in terms of
improvement by reduction of these surface defects without damaging the
image quality.  I have noticed slight color changes.  Bo suggests the
only reason this can now be attempted is due to Minolta's new software
offering an exposure adjustment.  However, I suspect that the problem
might be able to be resolved by either placing a diffuser right at the
light source, rather than between the film and the the light source (it
is actually attached to the film holder in some manner right now), or
also having the diffuser in the calibration slot of the holders so the
CCDS are adjusted with the diffusion material as a standard for the
light source.

Bo has put together a web site showing the results of two different
filter types.  I am not sure if the website is officially open to public
traffic yet, so I will ask him, and if it is, you can take a look if
interested in how the diffused lighting improved against the problems.

I am wondering if Minolta has installed any sort of condenser or other
method to collimate the lighting source, and if that isn't the problem.
  The fact that a diffuser resolves the majority of the problem suggests
they may have designed the lighting system incorrectly.

Under any circumstances, if you own a Minolta Pro, Dual Scan II or Elite
Scan II, (especially when using it with Kodachrome or B&W films) you may
want to consider the use of a light diffuser.

As soon as I get the OK, I will publish the website with more about this.

Art

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