[filmscanners] Re: Dark Lines on Negative Scans with HP5370C

["Arthur Entlich" <artistic-1@shaw.ca>]

Hi Gary,

This problem can be a few things, but all are hardware related.

Take a close look at the scan in something like Photoshop and zoom right
in to the pixel level.  Is the line you refer to distinctly affecting
one pixel width?  Also, try to view the scan with channel separation so
each channel is visible as a separate image, and see if the defect is
only showing up in one scan.  To do this is photoshop, you need to go
into the channel mode (rather than layers), and select one channel at a
time.  You may need to lighten each separation to see well.

If the problem is indeed on one color channel only, and is one (or more)
distinct pixels in width, then it is likely you have some defective CCD
element(s) in that CCD line.  This is usually not a user repairable
problem.  If, however, the edges are not distinct, and the area is soft
edges and involves a number of pixels, the cause could be a couple of
things.

Most likely is some dust either on the mirror or more likely, the CCD
area, partially blocking the elements.  Sometimes this can be resolved
by running some scan sequences with the scanner in different positions,
which might allow the dust to move or shift off the CCD sensor area.

However, another possible cause is dirt or damage to the calibration
strip which the scanner uses to calibrate each CCD element.  This strip,
which is usually glued on the underside of the top of the scanner
flatbed, is usually either white or black or sometimes a pattern of
both.  If this area is dirty or damaged, the scanner uses these
"endpoint" amounts to miscalibrate the CCD elements that correspond to
the damaged area, and can cause lighter or darker response from those
elements involved.  However, usually, this does not affect only one
color channel.

If the unit is under warranty, I recommend you have it sent it for repair.

Art

gtc@netrover.com wrote:

> Trying to scan large format Kodacolor negatives on an HP5370C flatbed
> scanner using Viewscan 7.5.3.9 and Windows 98SE.
>
> The scan produces one or more dark lines running in the direction of
> the scan.  The line(s) are most noticeable in lighter areas of the
> print such as light blue skies.
>
> They also appear to be restricted to the blue channel.  A number of
> the photos have large red objects in them.  The line(s) appear in the
> sky but end as soon as they reach the red.
>
> 35mm negatives scanned on the flatbed and a film scanner produce
> line(s) only on the flatbed.
>
> Am I right in thinking this is a hardware problem?  Any suggestions
> would be appreciated.
>
> Thank You.
>
> Gary Oliver


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