On 1/4/2014 11:18 AM, John Hudson wrote:
> I have not fared particularly badly with the supplied film carriers for my
> 9000. The glass carrier is indeed superior to the supplied carrier but I
> have yet to master the total elimination of Newton Rings which appear now
> and again despite being very careful about eliminating all signs of moisture
> on the glass and film surfaces. Somehow, these rings just seem to 'appen and
> they are a b***** to remove with PS.
Newton's rings are a phenomenon of optical physics; reflections between nearby
surfaces causing interference patterns.
<http://en.wikipedia.org/wiki/Newton%27s_rings>
They change color as the distance changes. I made a demonstrator of them many
years ago by simply putting black tape on
one side of a 6x6 glass slide holder. Light pressure on one side of the thin
glass would cause lovely rainbows that
shift around as finger pressure varies.
There is no way to eliminate them but to make sure there is either absolutely
no gap between film and glass, a gap
greater than that at which they form or use glass with a slightly not smooth
surface.
I suppose moisture may change how they appear, but is not a part of the
fundamental phenomenon. Some systems use an oil
with appropriate refractive index to connect film to glass without air gaps.
The real solution for that sort of film scanner is adequate DOF in the optics
for the glassless film holders.
Unfortunately, Nikon didn't provide that. One of the joys of the Canon 9950F
flatbed is good DOF. It can't hold a candle
to the 8000 in most ways, but is good on that one.
Ring Around the Moose
--
What if the Hokey Pokey *IS* what it's all about?
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