In a message dated Fri, 19 Oct 2001 4:22:32 AM Eastern Daylight Time, Arthur Entlich
<[EMAIL PROTECTED]> writes:
> The effect you are seeing is called Newton Rings, and it happens
> whenever two glossy surfaces come in contact. I believe the colors are
> determined by how many molecules of air are between the surfaces, a type
> of defraction.
It's "interference," not difraction. The surface of any transparent ojbect reflects
at least some of the light and that light then adds to or subtracts from the wave
front traveling towards it. Depending on the distance (as measured in wavelength of
light) between the two surfaces, the light at a given point becomes brighter or
darker. An anti-newton surface is simple a rough surface that doesn't reflect light
as uniformly as a very flat surface, so you don't notice the dark and light rings.
But the reflections and interference is still going on and has the result of reducing
the contrast of the image ever so slightly. The same thing happens in multi-element
camera lenses where reflections from each glass surface unavoidably reduce the
contrast of the lens. If you don't want to mess with glass anti-newton slide mounts,
you might consider upgrading your Nikon to a Polaroid. (On that issue, I agree with
Art and his comment that Nikons have more of a focus problem due to!
their weak light source and there
fore require corrective measures with curved film, such as using glass mounts.)
