hi steve
i use divided caffenol and dektol
because it lets me use a variety of films
in old cameras that have no exposure control ... without issue.
hi steve
i use divided caffenol and dektol
because it lets me use a variety of films
in old cameras that have no exposure control ... without issue.
I'm not up to date on this. I got good results with divided D23 back when thick emulsion sheet films were routine, but never liked how this method lowered the
acutance. Now when I want to capture a lot of luminance range in the subject, I just use a more appropriate film. I've earned my right to be lazy.
Originally Posted by Drew Wiley
Divided D23 is not a true divided developer of the Diafine/Pyrocat type in that some development begins in Solution A. I also found divided D23 it to be a low acutance developer, quite unlike Diafine and Pyrocat, which have extremely high acutance.
There are several strategies that can be used with film to capture an extremely long range of subject luminance values, but true two-bath developers like Diafine and Pyrocat have the unique ability to do this without having to take extensive exposure and subject brightness range notes. You just expose for the shadows, the method automatically prevents development beyond a relatively low CI which is ideal for scanning, but may or may not be ideal for printing directly from the negative.
Sandy
Last edited by sanking; 16-May-2016 at 13:13.
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I would like to ask a question...
The divided developer process is a develop-to-exhaustion process is it not ? The process relies on the film (or paper) absorbing one of the chemicals such that when placed into the second bath there is a reaction but it will exhaust itself eventually.
Yes ?
Yes, the film absorbs the reducer component of the developer in Solution A, then when the film is transferred to Solution B development takes place very rapidly. In fact, much of the develoment is virtually instaneouos as the reducer is exhausted almost instantly, as you see for example in working with developing out pt/pd. The sudden exhaustions is the mechanism that causes the creation of very pronounced adjacency effects.
Sandy
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Any process that is develop-to-exhaustion must then introduce a shoulder to the CI curve. The shoulder would be more pronounced for a thin emulsion type film simply because the film just cannot absorb very much of the first chemical.
It can never be that one develops over a longer period of time to get a proportionately increased density because the chemicals have been exhausted. Without looking at the instructions for Diafine I think they do say or imply that time and temperature are somewhat irrelevant for this reason IIRC.
Thus the more dense areas are compressed and the film just cannot distinguish between various dense values.
In this scenario, a highly exposed high-key negative would have limitations on being able to separate the high tones.
Yes ?
Just to answer my own post ... some text from the Diafine and Accufine instruction sheet ...
Diafine may be used within a temperature range
of 70 to 85°F with a minimum time of 3 minutes
in each solution. Increased developing times will
have no practical effect on the results. It is rec-
ommended that you do not exceed 5 minutes in
either solution.
I have copied and pasted from the document directly - please excuse the formatting.
Any process that is develop-to-exhaustion must then introduce a shoulder to the CI curve. The shoulder would be more pronounced for a thin emulsion type film simply because the film just cannot absorb very much of the first chemical.
It can never be that one develops over a longer period of time to get a proportionately increased density because the chemicals have been exhausted. Without looking at the instructions for Diafine I think they do say or imply that time and temperature are somewhat irrelevant for this reason IIRC.
Thus the more dense areas are compressed and the film just cannot distinguish between various dense values.
In this scenario, a highly exposed high-key negative would have limitations on being able to separate the high tones.
Yes ?[/QUOTE]
Some of your points/questions would require empirical data to address. In terms of highlight compression, I have never found that to be a problem with divided development with either Diafine or Pyrocat. Actual curves plotted from divided development are in fact quite linear, with very little toe and/or shoulder. You can see one family of curves in the article, which is a real family of curves from film developed in divided Pyrocat.
Sandy
For discussion and information about carbon transfer please visit the carbon group at groups.io
[url]https://groups.io/g/carbon
The Diafine instructions are what they are, but don't expect general directions like this to apply equally to all films. Emulsions are very different in the way they are able to absorb reducer, and the Diafine instructions provide no solution to address this issue in the manner of mixing and dilutions.
Sandy
For discussion and information about carbon transfer please visit the carbon group at groups.io
[url]https://groups.io/g/carbon
ive developed several "runs" of film using 1L of chemistry
and the sumatranol .. i have 3-4L mixed, that i have used for
4 - 5 months a a time withott mixing new
YMMV
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