[filmscanners] Re: "Halo" Effect

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

Dear Joe,

Thanks for the additional info.  I tend to agree that those tests do
lead one to the conclusion that the problem is with the scanner optics,
since orientation of the slide shouldn't alter the position, intensity
or directionality of any halo or fringing effect, unless it is indeed
being created within the optics of the scanner.

Have you ever brought this matter up with Polaroid?  Have you tried
using manual focus (I think its available via Vuescan and Silverfast) to
see if this might alter the amount of the halo effect?

I wonder if other scanners are less likely to manifest this problem.  I
seem to recall that someone here years ago was having a similar problem
with an Acer Scanwit, but I don't recall if any solution was found.

Art

Joe Pedit wrote:

> Hi Art,
>
> Thank you for your comments.  I left out some additional information for
> the sake of brevity in my original post.  I also scanned the slide
> (Provia 100F) in different orientations (e.g., sideways, upside down,
> reversed) to check if the blue and red flares were a scanning artifact.
>   The flares noted in my original post do not follow the stars when the
> orientation is changed.  Instead, their size and location is always
> proportional to the vertical distance from the centerline as seen by the
> scanner.  In the original scan, a star located near the center of the
> left edge would not have the red and blue flares.  When the slide is
> rotated 90 degrees clockwise, from the point of view of the scanner the
> star is now located near the center along the top edge.  That star would
> now show the red and blue flares when it did not in the original scan.
> It was based on this additional information that I assumed the red and
> blue flares were a scanning artifact.
>
> I would like to use slide film (E200, Provia 100F and 400F) for my
> astrophotography because of its higher contrast, lower grain, and lower
> reciprocity failure compared to color negative films (Supra 400, Royal
> Gold 400).  Unfortunately, the flares and other problems associated with
> scanning dense slides make the use of slide film difficult with the SS4000.
>
> Joe
>
>
>


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