[pure-silver] Re: donut solution; enlarger lens problem
- From: Georges Giralt <georges.giralt@xxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sat, 12 May 2007 08:49:28 +0200
Shannon Stoney a écrit :
I think I get it. You're saying that it's ok for the frosted glass to be
on top, because then it's like the ground glass in the camera: not
between the negative and the lens. Is that right?
Ok, so I did it right: I put the frosted glass on top, touching the
base of the film. Why did I still get Newton rings? I thought the
purpose of the frosted glass was to discourage Newton rings, but
apparently it didn't work. The 4x5 carrier just has plain glass and
there were no Newton rings and never have been, even though the glass is
in contact with the film base.
IMHO, the problem encountered here is not newton rings. It is flare. And
this is why the different carriers provide different results.
THis flare was caused by reflexion by the paper on the baseboard or into
the enlarger bellows and the condenser system of the enlarger. Maybe the
two carrier are of different colors ? Or one has chipped paint showing
the metal base ? As your negative is not 4x5, try print using the good
size neg carrier and put above it or above the negative a piece ob black
drawing paper with an opening just sufficient to discover the negative
to print.
If the problem was from flare, it won't show, if from newton rings, it
will...
What does anti-Newton-ring glass look like? Maybe that's not what this
glass actually is. The guy that set up the enlarger for me told me
that's what it was, but maybe he was wrong.
Anti newton rings glass looks like ordinary glass but has one side
really lightly frosted. It is quite subtle. But if you look at it from
an angle, you'll see that the surface is not smooth. As it is really
light, it is quite difficult to see. But this is this unsmooth surface
which has to touch the film base to break the perfect surface contact.
It is better to compare with plain glass and check reflections to
distinguish between non frosted and frosted surfaces.
--shannon
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