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>
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
wrote:
On 4/17/2015 12:01 PM, Janet Gable Cull wrote:
Richard, will you describe "edge effect"? I wonder if that's what Idevelopment at the border of a high and low density area. The nature of
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
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
WB6KBL
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