John,
RE: Kodachrome/standard by which others are judged .... 70-odd years and
still going strong - in one form or another.
And thanks for the dissertion on the processes
Cheers,
Lee
----Original Message Follows----
From: "John A. Lind" <jlind@xxxxxxxxxxxx>
Subject: Re: [OM] Slide Film/K14
What about Rocky Mountain Film Lab' in Colorado? I don't know whether this
is the same K14 process, but ....
http://www.rockymountainfilm.com/
http://www.rockymountainfilm.com/oldfilm.htm
http://www.rockymountainfilm.com/newfilms.htm
http://www.rockymountainfilm.com/K14movie.htm
I recently bought an old camera that had a roll of Kodacolor-X 20-exposure
that was nearly used up. Assuming a few people (like I did when I bought
it) snapped the shutter a time or two after it was bought at an estate sale
it might have a dozen or so shots on it. I don't hold much hope of anything
- but can't bring myself to throw it in the trash.
Cheers
Lee
Kodacolor-X is C-22, the color negative process prior to C-41. Rocky
Mountain will certainly handle K-14 (135 size). I don't know if it's done
in house or sent to one of the other labs. *Original* Kodachrome is K-11.
Kodachrome II, Kodachrome-X and Kodachrome-F are K-12. These are the prior
processes, and the chemistry is no longer available for them. Rocky
Mountain will process it in house, but cannot do anything more than create
B&W negatives from it. All chrome film is essentially structured like color
negative film except it's optimized for reversal and does not have an orange
mask. The basic developing process begins as for color negative. The
"reversal" occurs when what is initially developed is bleached out and what
remains is then "flashed" chemically, equivalent of exposing it completely.
That is then developed.
What makes Kodachrome different is its lack of dye couplers in the emulsion.
These must *also* be added to each layer. The result is a much thinner
emulsion, one of the reasons for the shape of its MTF curve and its apparent
sharpness in spite of slightly higher diffuse rms granularity numbers.
Kodachrome can be developed to B&W negative. Also, IIRC, if Kodachrome is
cross-processed in E-6 it comes out as a B&W positive. How good it looks or
whether it screws up the E-6 chemistry (for other E-6 processing) I don't
know. From top down, Kodachrome has the following emulsion structure:
* Blue layer
* Green layer
* Red layer
* Film base
The K-14 process develops each layer separately:
* First developer to bring up a negative B&W image.
* Exposure to pure red light through the film base side.
* Cyan developer and cyan dye coupler introduced.
* Exposure to pure blue light from the emulsion side.
* Yellow developer and yellow dye coupler introduced.
* Chemical fogging of remaining silver halide (all in the green layer).
* Magenta developer and magenta coupler introduced.
* Bleach all developed silver back to silver-halide, fix it into
solution and wash it out.
Note: There are a total of 14 steps; I have left out some washes, etc.
The unique processing of Kodachrome using the introduction of the dye
couplers during developing solved the problem of dye coupler migration to
other color layers, one that both Agfa (the other film giant at the time)
and Kodak were pursuing in a technology race during the 1930's. Leopold
Mannes and Leopold Godowski, who were professional musicians and amateur
photographers, jointly created the prototype for Kodachrome at Kodak's lab.
This was done at the invitation of Dr. Mees, founder of Kodak Research
Laboratories. The pair had originally talked to George Eastman who
dismissed it. Mees saw potential that Eastman didn't. Kodak introduced
Kodachrome first in 1935 as a cinema film. Kodachrome may be a complex
process, but it's not as cumbersome as Technicolor. It was introduced as
35mm still camera film a year later in 1936.
Dr. Gustav Wilmanns and Dr. Wilhelm Schneider at Agfa finally solved the dye
coupler migration problem to create Agfacolor Neu in 1936 (to distinguish it
from Agfacolor, a "screen film" which used a single layer of miniscule,
colored resin particles on top of a B&W emulsion). All current color films,
with the sole exception of Kodachrome, are based on the technology used to
embed dye couplers in the emulsion layers that Wilmanns and Schneider
created for Agfa.
By comparison, E-6 process starts with a first developer to bring up the B&W
negative, but then uses a single fogging and development reversal process as
the dye couplers are already present in the emulsion. It's all done in 6
steps, less than half that required by Kodachrome. In addition, the colors
apparently cling tighter to the grains in Kodachrome than in the E-6 films.
The E-6's require finer granularity than Kodachrome to achieve similar
apparent sharpness, especially when combined with a thicker emulsion (edge
definition degradation from oblique ray paths through the emulsion).
Kodachrome has always been, and **remains** The Standard by which all other
color transparency films are compared, in accurate color rendition, apparent
sharpness, color gradation, and archival life.
-- John
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