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filmscanners: Re: Emulsion flaws (was dust in SS4,
At 9:20 AM -0400 9/23/01, Tom A. Trottier wrote:
>I find this all very puzzling. I'd suspect your water if it hadn't
>been "double distilled."
Thanks for your interest, and suggestions. They are all good,
but as you will see in the next line below, they don't apply to the
present situation, but that's my fault.
I have to retract part of my previous statement about the
"bubbles" not appearing in undeveloped film.
Both Art Entlich and I had trouble believing that bubbles (or
whatever they are) could form, during developing, in the protective
layer over the emulsion, so I had another look through the microscope
at a piece of undeveloped Kodak Elite Chrome film. Using very careful
lighting and focussing, I now see that the "bubbles" are indeed
present in undeveloped film. They are just very hard to see against
the very dense background. Sorry to be so misleading on this matter.
It does make largely irrelevant any question of this phenomenon being
caused by quirks in developing or drying the film.
The question still remains - do these "bubbles" cause some of
the "dirt spots" many of us see in the lighter areas of our scans. I
put an Ektachrome 64 Tungsten slide, which contained a lot of white
subject matter, under a dissecting microscope at 80x magnification.
The bubbles were extremely visible and appeared similar in size to
some of the "grain clumps" or dye clouds forming the image. If Tony
Sleep and others are correct about the grainy appearance in scanned
images being caused by aliasing effects between the scanner CCD
(particularly in 2700 ppi scanners) and the "film grain" then it
seems to me these highly visible "bubbles" should also have some
I'd like to know if they are visible in a 4000 ppi scanner,
and if so what appearance they have. If someone with one of these
wonderful machines would like to scan a few slides containing a lot
of light or clear area, (which is the only place the bubbles would be
easily visible), I would be interested to see the results.
Whether or not they are visible in prints is another question.....