What follows is transcribed from The Handbook for Contemporary Photography, 4th Edition by Arnold Gassan. 1977. Arnold was a professor of mine at Ohio University and I don't think he would mind me sharing this with everyone, I think it interesting and still useful.
Contrast Control through Developer Dilution
"Another way of controlling contrast...is through varying the dilution of the developer. This is a very useful control with some of the liquid concentrate stock solutions, and of these the Kodak HC-110 developer offers exceptional qualities.
Contrast control through developer dilution uses the high energy HC-110 with its almost unique ability to provide very clean separations of shadow densities and also offer linear separations of all equal exposures into the high densities, even though diluted to a very great degree. The effects of varying developer dilution for HC-110 and Tri-X rather than developing time can be seen by examining figure 4-31. (see attached) These curves show the equal separation in the shadows and also the contrast variations possible by merely varying the concentration of the HC-110 while keeping time, temperature and agitation constant.
The advantage of this system is that a widely distributed, very stable, highly concentrated commercially available developer of known quality is used only at a standard time-- one which is physically long enough to avoid problems inherent in short developing time. The concentrated syrup can be measured accurately with pipettes, or this simple two step dilution schedule can be employed:
Make a working stock of 1 part developer and 9 parts water.
Do not mix more than what will be used in a few days.
Distilled water is recommended.
From there dilute working stock in dilutions from 1:30 to 1:80"
Gassan provides some recommended dilutions for a variety of films, but bear in mind two things:
These dilutions are from the above stock solution, not from the syrup, and this info is from 1977, so films have changed, but the main thing is that he finds that a "decade change of dilution e.g. a change of 1:50 to 1:60 approximates a paper contrast grade". (for Kodak films, see below)
All film is developed in HC-110 at 21C -70F for five minutes with standard agitation.
Kodak films
Pan X Plus X Tri X
N++ 1:50 1:50 NR
N+ 1:60 1:60 1:30
N 1:70 1:70 1:40
N- 1:80 1:80 1:50
N-2 NR NR 1:60
Ilford films
PanF FP-4 HP-5
N+ 1:50 1:55 1:55
N 1:60 1:60 1:60
N- 1:70 1:65 1:65
N-2 1:80 1:70 1:70
Gassan based these dilutions on a goal of developing a highlight density-- zone VIII, to a density of 1.15 above FB+F. He concludes: " The whole purpose of this control system is to produce high quality, low density negatives that will print easily and well, rather than to "push" film.
Hope this is of interest.
--erik
Contrast Control through Developer Dilution
"Another way of controlling contrast...is through varying the dilution of the developer. This is a very useful control with some of the liquid concentrate stock solutions, and of these the Kodak HC-110 developer offers exceptional qualities.
Contrast control through developer dilution uses the high energy HC-110 with its almost unique ability to provide very clean separations of shadow densities and also offer linear separations of all equal exposures into the high densities, even though diluted to a very great degree. The effects of varying developer dilution for HC-110 and Tri-X rather than developing time can be seen by examining figure 4-31. (see attached) These curves show the equal separation in the shadows and also the contrast variations possible by merely varying the concentration of the HC-110 while keeping time, temperature and agitation constant.
The advantage of this system is that a widely distributed, very stable, highly concentrated commercially available developer of known quality is used only at a standard time-- one which is physically long enough to avoid problems inherent in short developing time. The concentrated syrup can be measured accurately with pipettes, or this simple two step dilution schedule can be employed:
Make a working stock of 1 part developer and 9 parts water.
Do not mix more than what will be used in a few days.
Distilled water is recommended.
From there dilute working stock in dilutions from 1:30 to 1:80"
Gassan provides some recommended dilutions for a variety of films, but bear in mind two things:
These dilutions are from the above stock solution, not from the syrup, and this info is from 1977, so films have changed, but the main thing is that he finds that a "decade change of dilution e.g. a change of 1:50 to 1:60 approximates a paper contrast grade". (for Kodak films, see below)
All film is developed in HC-110 at 21C -70F for five minutes with standard agitation.
Kodak films
Pan X Plus X Tri X
N++ 1:50 1:50 NR
N+ 1:60 1:60 1:30
N 1:70 1:70 1:40
N- 1:80 1:80 1:50
N-2 NR NR 1:60
Ilford films
PanF FP-4 HP-5
N+ 1:50 1:55 1:55
N 1:60 1:60 1:60
N- 1:70 1:65 1:65
N-2 1:80 1:70 1:70
Gassan based these dilutions on a goal of developing a highlight density-- zone VIII, to a density of 1.15 above FB+F. He concludes: " The whole purpose of this control system is to produce high quality, low density negatives that will print easily and well, rather than to "push" film.
Hope this is of interest.
--erik