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[filmscanners] Re: Noise in Polaroid SS 4000 scans



Hi Harry,

If you send me a small section of the image (about 1/8" x 1/8" at
original 100% size of the frame, 8 bit, not 16 bit) (my email cuts at
about 1.5megs, so make the image size such that an uncompressed 8 bit
scan will be under 1.5 megs, please), I will look at it and see if I can
determine if the problem is grain or noise or both.  I find some
negative films, when underexposed can produce very large grain in the
areas that are "dark" when reversed to positive.

By the way, if you are seeing a lot of noise in the dark areas of the
positive image (when the film is a negative film) it is very unlikely to
be noise.  Noise mainly shows up in the most dense areas of the film,
since that is when it approached the noise floor of the scanner sensor,
so you'd expect to see it in the darkest areas of slides/transparencies,
and the LIGHTEST areas of the positive representation in scans of negatives.

If you are seeing a lot of "noise" in the dark areas of the positive
representation of a negative, it is likely not noise, but grain.

Art

harry@vdkrogt.nl wrote:

> I have this scanner for about 2 years nows. I can remember that I was
> very excited to see the results after my LS 1000 broke down. At that
> time I also was a bit surprised to see more noise than in the Nikon
> scans, but I figured it was 'more details and film grain'. Not a very
> good attitude looking back. When I got my new Mac G4 with 17 inch Studio
> Display I was surprised to see so much red and green dots in the dark
> parts, that was when I got a bit puzzled. But then you think it might be
> the sharpness of the display. I also think that when something 'strange'
> happens with computers, in most cases it's the person operating them and
> wrong settings are the cause of the problems.
> I never opened the scanner for cleaning, and never used a dust cover.
> One year ago I had the 'continuous focussing or was it ejecting' error
> and it was send to Tech Support in the Netherlands. I sent a CD with a
> scan with the question if this noise level was normal behavior, they
> said it was. So I just lived with it. But lately I feel that I am not
> comfortable with it, also because I want to know if there is something
> wrong with my workflow.
> I scanned at 4000 dpi and this indeed seems less noisy, and more grainy,
> although noise remains. If so, then the combination of de Fuji NPS 160
> and my lab might be less then optimal, because I feel such a big grain
> is not normal for 160 film.  I use a one hour lab to process the films,
> that might cause a problem. And it might be the combination of film and
> the scanner of course.
> I am a bit surprised to see that the opinions are so different, grain
> versus noise.
> What can I do to make a more definite test? Make scans at 4000 dpi and
> put them on the page? That would mean even more bandwith.
>
> Harry
>
>
>


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