[filmscanners] RE: Avoiding Newton rings

["Paul D. DeRocco" <pderocco@ix.netcom.com>]

Newton rings are caused by small variations in the distance between two
reflective surfaces. If the surfaces are perfectly parallel, there will be
no Newton rings; if the angle between the surfaces is sufficiently great,
there will be no visible Newton rings. Only when the surfaces are almost
parallel do you see the artifacts. Since we're talking about variations on
the order of a few wavelengths of light, there's not much you can do at the
macroscopic level that humans operate to control this effect. About all you
can do is use a mount that has anti-Newton texturing on it (a very slight
matte finish). However, it will blur the image, so I've found.

I'd like to find a better way to flatten out buckled transparencies. I
wonder if there's some sort of heat treatment...

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

> From: Anthony Atkielski
>
> I use the glass 120 film holder on my LS-8000ED because I need to
> be able to
> hold the film flat, however, I have a lot of trouble with Newton
> rings.  The
> weird thing, though, is that some images have multiple instances of the
> rings, and others have none.  This implies that the rings are not
> inevitable
> when scanning, only common ... so there must be a way to avoid them.  What
> causes the rings on some images but not on others, and what can I do to
> avoid them when preparing and loading the film?

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