I can't believe this is almost 20 pages by now. Haven't we already debated this same stuff out in 10 other threads before, guys?
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.
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I also believe (without any chemical knowledge) that this could be the sources of the streaks due to higher concentrations locally.
Originally Posted by Michael R 1974
But what is the process that's going on:
1) heavier elements are sinking down, thus causing extra development from the bottom up;
2) lighter elements float to the suface, thus causing extra development from the top down;
3) heavier elements are sinking down, thus reducing development from the bottom up;
4) lighter elements float to the suface, thus reducing development from the top down?
All four seem theoretically possible, at least to me.
What are the chemicals that cause the effect and are they heavier or lighter than water?
Also, do we know if the side with the light streak was on top or at the bottom in the tank?
So maybe in the next test making a mark in the film (cutting out a sprocket?) to mark the top side?
And maybe develop a second part of the film under the same conditions, but with some minor agitating, say three or four times, to see what the effect is?
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In general, there are many variables. The emulsion releases bromides which can act as restrainers, and other compounds (halides, silver, dyes etc). Different developing agents have differing sensitivities to bromides, and sensitivity depends on pH. Local pH can be affected by development by-products which tend to be acidic, so buffering can come into play. Oxidized forms of some developing agents can be more or less active than the initial compound, and the effect of sulfite on these oxidation products can either increase or decrease the rate of development. Diffusion in different directions within the emulsion. Aerial oxidation. Convection currents. These variables are interrelated.
Also, these things are dependent on the amount of development taking place locally. More bromides and reaction products build up where there was more exposure and more silver is being developed. So the actual image being developed can have an important effect depending on where the areas of high and low exposure are relative to eachother.
There is also the risk of unevenness resulting from non-uniform wetting, diffusion etc. at the very beginning of development. This is one of the reasons why a pre-soak is usually recommended with stand methods to help promote uniformity at the beginning of development.
Put it all together and it becomes obvious why a technique like stand development requires experimentation and practice. With some combinations a full stand procedure may work fine. With others, some amount of minimal agitation may be required.
great thread !
ming, some caffenol folks ( over on flickr in the palace )
use salt in their caffenol developer to reduce fog ..
its fun to see other folks experiment with it ...
did you get a chance to print any of your experiments ? some
salty film looks better electrified, some looks better contact printed, and others look best enlarged
i guess the trick with film is to dovetail the whole chain .. film>dev> what type of print ...
don't stop having fun and experimenting, its when you get off the main road you see the good-stuff.
and don't listen to the nay-sayers, sometimes they just enjoy stepping on everyone's buzz ...
couldn't agree more tom !
Originally Posted by Toffle
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Increase development and print on softer paper to minimize grain.
That's a good theory too ic^. Would a soft paper dev also help? Something like this?
LegacyPro Select Soft Paper Developer to Make 1 Gallon
Great thread, imo. That NB23 guy is a little unsavory but overall there has been a lot of great discussion so far. FWIW I stand develop my film about 50% of the time and after getting the recipe down, have had consistent results that I am happy with.
Michael, correct me if I'm wrong but there are no bromide ions released when using Rodinal thus making bromide drag a non factor?
If I might cut in, the bromide ion comes from the film itself it is released during development. Thus during stand development it is concentrated at the surface of the film. This is what causes bromide streaking. Any bromide ion originally present in a developer is evenly concentrated throughout its volume. This is why any agitation is preferable even if it is only intermediate agitation.
Originally Posted by tron_
One of the standard ways of minimizing grain is to under develop a film and use a higher contrast paper. This is the method recommended for 35mm film and was advocated by Willi Beutler in his book. Doing the opposite would actually increase grain.
Last edited by Gerald C Koch; 07-19-2013 at 11:26 AM. Click to view previous post history.
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tron: as noted in my post bromides (and chlorides/iodides in smaller amounts) are released by the film emulsion.
Originally Posted by tron_
In response to Gerald and ic-racer, that has always been an interesting question. The prevailing wisdom is to develop film to a lower CI and increase paper grade. But depending on the film, developer and subjective considerations ic-racer's opposite proposal may or may not work too. The question in any particular case is whether the difference in film granularity from developing the film to a lower or higher CI has a greater, lesser or equal/offsetting effect in comparison to the change in paper contrast.
I suspect in most cases the increase in graininess associated with higher contrast printing is 'smaller' than the decrease in film granularity resulting from reduced film development (ie you're slightly better off developing film to a lower CI and increasing print contrast) but this could vary. There would however typically be other benefits to developing the film to a slightly lower contrast as decreased granularity can have a beneficial effect on acutance and fine detail (or what has been referred to in the literature as "detectivity").
Last edited by Michael R 1974; 07-19-2013 at 11:44 AM. Click to view previous post history.