Last I heard, Kodak, Fuji, Agfa, et al. do not have some special process
whereby they place individual grains on a film - never have, never will.
Photosensitive chemicals and dyes of various thicknesses and concentrations
are mixed in a gelatin and coated onto a base. No grains, no clumps, nothing
but a gelled solution of (and they are very small) molecules. The grain
doesn't come into existence until a photon or a number of photons enter the
emulsion and change the chemical composition of the photosensitivity
material - change individual molecules. Now, as I understand it, a "grain"
can consist of one or many of these new molecules that clump together within
the gel and that clumping depends on proximity and with more light comes
more changed molecules, closer together giving greater tendency to clump.
Further it's all random. This produces a different effect on the appearance
of sharpness. A star will light up one of the cells in the photo array,
regardless of whether it's centered on one of the pixels or near it's edge -
digital position noise. The same star will be generally centered on the
grain(s) it creates regardless of where it strikes the film.
I suspect that this battle will rage on for some time to come.
Earthbound Astronomers still use plate film for the sharpest, finest
detailed photos.
Regards,
Bob...
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"The art of taxation consists in so plucking the goose
as to obtain the largest possible amount of feathers
with the smallest possible amount of hissing."
- Jean-Baptiste Colbert,
minister of finance to French King Louis XIV
From: "Godfrey DiGiorgi" <[EMAIL PROTECTED]>
Offered to the PDML as basis for another discussion:
http://www.luminous-landscape.com/essays/clumps.shtml
