[rollei_list] Re: Anti Newton Ring Glass Effect on Enlarging
- From: Don Williams <dwilli10@xxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 29 May 2009 16:39:35 -0500
At 08:58 PM 5/28/2009, Dick wrote, in part:
There are two ways of preventing Newton's rings: one is to use a
slightly roughened surface on one side in order to break up any
coherent reflection; the other is to use an anti-reflective coating
on the surface of the glass. The first is acceptable and works well
when it is in contact with the support side of a negative. Since the
emulsion surface of some color materials is as smooth as the support
side there can be Newton's rings formed on the emulsion side as well
as the support side and generally speaking one wishes to avoid any
diffusing surface in the image path.
In a prior note I said I thought in "olden days" corn starch was used
to prevent them in glass-mount enlargers. Could that have been
powdered cellulose instead?
Or am I just dreaming this all up?
I'm told that I'm losing my mind...
but I don't miss it. :)
Don Williams
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