[pure-silver] Re: Newton... Re: donut solution; enlarger lens problem
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 11 May 2007 21:59:37 -0700
----- Original Message -----
From: "Peter De Smidt" <pdesmidt@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, May 11, 2007 10:20 PM
Subject: [pure-silver] Re: Newton... Re: donut solution;
enlarger lens problem
Some emulsions sides of film can be shinier than they used
to be, and this can lead to newton's rings between the
emulsion side of the film and the lower glass in the
carrier frame. For example, Howard Bond has anti-newton
glass both above and below his large format TMX and TMY
negatives. He says that there isn't any apparent
degradation from the lower glass, but this would depend on
the fineness of the anti-newton glass and the
magnification. In other words, coarse anti-newton textured
screens and/or high magnification make degradation more
likely.
I don't know if anyone has made anti-Newton-ring glass
using an anti reflection coating similar to that used on
camera lenses but I think it would work. There is such glass
made for mounting artwork to reduce the reflection of
ambient lights so it should not be too expensive, at least
for a trial. The index of refraction of both gelatin and
support are greater than air so the coating may not be
effective for them but if it works it would be better than a
rough surface.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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