More interesting hits on Rodinal:
http://unblinkingeye.com/Articles/Rodinal/rodinal.html
Rodinal using Tylenol
http://www.drfrankenfilm.com/diy-rodinal/4575179217
Yet another version:
http://www.digitaltruth.com/data/rodinal.php
Note that the Wikepedia article on Rodinal claims its sharpness
is due to not having a silver solvent. This is nonsense, silver
solvents, like sulfites, do not affect sharpness or resolution of the
image. Their action is on a much smaller scale. Rodinal when diluted
tends to produce edge effects as I mentioned before. Sulfite does tend
to reduce edge effects because it tends to change the reaction products
of the developer. Some sulfite is necessary to prevent the developer
from oxidizing rapidly and also to prevent staining of the emulsion from
the reaction products of some developing agents. Where staining is
desired, as with some pyro formulas, the amount of sulfite or other
preservative must be limited. There ARE non-staining pyro developers.
When pyro was very popular for use for motion picture negative
development the stain was considered undesirable and a number of
formulas were worked out to eliminate it.
Also, the first site I linked mentions the use of eosine. None of
the other sites do. I am not sure what function eosine would have in a
developer but I think the formulas using potassium hydroxide, and
potassium metabisulfite are probably pretty close to the original AGFA
formula. BTW, AGFA made a lot of potassium as by-products of its
general chemical manufacturing so it was very cheap for them to use
potassium compounds.
On 4/17/2015 5:49 PM, Janet Gable Cull wrote:
Thank you, all!
On Fri, Apr 17, 2015 at 4:34 PM, Eddy Willems <eddy@xxxxxxxxxxx <mailto:eddy@xxxxxxxxxxx>> wrote:
TRI-X ISO 400 20° C 1+50 8'30
1' prewash
best regards
Gary Marklund schreef op 17/04/15 om 22:17:
OK, You have my attention. I just went into the darkroom and I
have two bottles of real Rodinal. A 500ml bottle that was opened
(and probably used once) in 2005. I shook the bottle and it
gurgled like it was new. The other bottle is a 125ml bottle that
has never been opened, still has original Rodinal notes folded
over the top of the boxed bottle).
My M6 has been screaming "Feed Me!" for some time. Like Janet,
I'm interested in using it with Tri-X (also Ilford delta 400).
Comments and E.I. and development times more than welcome.
Thanks,
Gary
On Fri, Apr 17, 2015 at 1:08 PM, Gary Marklund
<garymarklund@xxxxxxxxx <mailto:garymarklund@xxxxxxxxx>> wrote:
OK, You have my attention. I just went into the darkroom and
I have two bottles of real Rodinal. A 500ml bottle that was
opened (and probably used once) in 2005. I shook the bottle
and it gurgled like it was new. The other bottle is a 125ml
bottle that has never been opened, still has original Rodinal
notes folded over the top of the boxed bottle).
My M6 has been screaming "Feed Me!" for some time. Like
Janet, I'm interested in using it with Tri-X (also Ilford
delta 400).
Comments and E.I. and development times more than welcome.
Thanks,
Gary
On Fri, Apr 17, 2015 at 12:45 PM, `Richard Knoppow
<dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>> wrote:
On 4/17/2015 12:01 PM, Janet Gable Cull wrote:
Richard, will you describe "edge effect"? I wonder
if that's what I observed in my friends scans that I
like. I wonder how and why it would do that? Does
it somehow perceive the light and dark of an image,
and treat them differently?
Edge effects, sometimes called border effects, are
variations in development at the border of a high and low
density area. The nature of the effect depends on the
developer, specifically on whether its reaction products
suppress or enhance development. The effects are very
localized because they are due to diffusion of the
developer reaction products in the emulsion. The usual
effect is to increase the contrast at the edge. Because
the effect depends on reaction products its increased
where the developer is highly diluted or where there is
insufficient agitation to wash away reaction products at
the surface and bring fresh developer there. When the
effect is not extreme it enhances sharpness. Note that
this is sharpness not resolution. Sharpness developers
were long popular for 35mm use because they tend to
compensate for the lack of sharpness caused by
insufficient film and lend resolution. More modern films
have better resolution. However, the eye tends to judge
sharpness by edge contrast so a high resolution but
relatively low contrast image will look less sharp than
one with high edge contrast but considerably lower actual
resolution. Extreme edge effects can look like someone
drew lines around objects. This used to be a serious
problem with motion pictures because the release print
was often several generations from the original. Each
generation increased the edge effects until one got "edge
crawl". Edge effects and compensation are related since
both depend on local exhaustion of the developer.
Dome developers, notably hydrquinone, have reaction
products that tend to accelerate development while
others, like metol, tend to suppress it. Some
combination developers have little edge effect due to the
mutual cancellation of the effect by the developing
agents. Nonetheless, developers like D-76 will become
edge effect developers when diluted to 1 part stock to 3
parts water or more.
-- Richard Knoppow
dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>
WB6KBL
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