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filmscanners: Nikon LS-30: High contrasts in slides cause halos!

Hi everybody,

a couple of days ago I addressed the list for advice as to replacing a
defective Nikon LS-30. Fortunately (or, maybe not), the damage was not
as big as I thought and the lens that caused the trouble (it had
suffered from exhaled solvent that had emerged from a microscopical
object in a slide frame which I had scanned before) could be replaced.

I have always had a problem with getting sharp scans out of slide film -
they always appeared as if taken through a softening filter, with
apparent halos at the outlines, especially white-black transitions. I
thought the lens change might be a remedy for this as well.

I was mistaken. Please take a look at http://schmode.net/halos.jpg and
http://schmode.net/halos2.jpg - what makes this an issue is that the
second image crop was taken with the scanner being almost new, just
three months in use. This can't possibly be dirt; there must be a
serious problem *by default* with at least some LS-30 scanners as to
scanning transparencies.

The problem does not occur with negative films, and it's not as bad with
low contrast slides (though visible as a slight loss of crispness). I
have now dismantled the unit completely to find out what's going on,
checked all of the optical path - nothing. My presumption - which would
be a really bad thing if true - is that the "structure" of slide film
(you can "feel" the image with your fingertips, meaning the dye layers
have "edges") causes diffraction of the light passing the slide, causing
light to seep into areas of the CCD where it actually shouldn't.

What I wrote last week - my next scanner would be a Nikon again - is not
true any more. I have no confidence whatsoever in their products. I am
going to order a Minolta Scan Elite II as soon as it is available in
Germany. And I'd advise all the Nikon owners to critically check what
they get out of their slides. I am not going to argue with Nikon on that
matter - they have a history of non-cooperation that I just don't want
to waste my time for adding another chapter to it.  

Best regards -

My animal photo page on the WWW: http://schmode.net
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