Rodinal Developer

Rodinal is a film developer, the recipe of which was introduced by Agfa in 1892 and which has been actively used since then despite the fact. Acutance enhancing film developer. RODINAL is produced acording to Agfa Leverkusen´s latest Rodinal. formula from 2004. It does not get more RODINAL.

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On this page I would like to present and share with all b&w enthusiasts a technique I use, which enables me to obtain good sharpness and grain combined with a very wide tonal range.

Before I start - a point of precaution: don't rush to use this technique on an important roll of film - you have to experiment to find your own working point, and become comfortable with the process and results. For example, as you will see, a very diluted developer is used - so quality of water used to prepare the working solution becomes a factor of grate importance.

It would be wise to point out that any development recommendation can only be a starting point for your further experimentation. My advise is to start with a longer than suggested development time, and fine-tune it according to results. If the negatives are to contrast - reduce the development time or vice-versa.Development time I give here

Introduction.
The technique, known as 'Compensating Development', was mentioned in several publications but did for some reasons did not become very popular. I personally learned about it from Bill Pierce 'Nuts & Bolts' column in Popular Photography (dated August 1976, I still have this issue..). I thank Bill and PP of those days, when they were providing plenty of useful information and supporting photographers not camera makers.

The technique was originally applied to very slow b&w films (ASA 25~50) which offer extremely fine grain and very high sharpness but at an expense of very harsh negatives which fail to deliver a full range of tones, from shadows to highlights, in the print. This is where the 'Compensating Development' comes to rescue - to provide the tonal range without sacrificing grain and sharpness.

Note: from my experience the technique can be as successful when applied to today's modern ASA 100~125 b&w films.

The benefit of using slow films .
Many studio and nature photographers, whose controlled and static subjects allow them to use slow films, can now obtain grain and sharpness in prints from 35mm negatives easily rival the results that we associate with medium and even large format work. And the range of tones and shadow details can rival that produced by ASA 100 to 400 films.

The benefit of using dilute developer .
Any dilute developer offers the advantage of consistent, one-time use and longer, more controllable, development times. The 'compensating' action of the dilute developer will prevent highlights from blocking when adequate exposure is given to insure shadow detail.

Compensating Development.
When film is immersed into a diluted developer and left undisturbed for a long time, the developer over the dense areas exhausts and blocks the fresh developer from diffusing toward the emulsion so the developing action gradually slows down. At the less dense areas the developer has enough time to apply its entire strengths. The result of this process is that the less exposed areas were more exposed to development action while the darker areas where blocked and suffered less intense development.

Edge sharpness (acutance) is enhanced by an even more complex developer response to those areas where dark and light tones abut. What happens at these areas is that weakened developer, exhausted over the dense area, diffuses into less dense areas, thus giving them even less development. In the opposite direction vigorous developer, less exhausted from its easy task over the thinner areas, bleeds over into dense areas thus giving an extra push. Since the transfer mechanism is diffusion, the process occurs only along contours of rapid change in film density and the result is darkening of the dark border and lightening of the light border, effect which has a visual interpretation of increased contrast and enhanced sharpness. Some image processing software (PaintShop, PhotoShop, etc.) provide 'Sharpen' or 'Sharpen Edges' filters - the algorithms implemented to boost sharpness are based on same visual phenomena.

Why Rodinal ?
Rodinal seems to be most suited to be used at high dilutions of up to 1:200. Many believe that at an extreme 1:100 dilution Rodinal shows its greater advantages over more conventional formulas. Rodinal can produce very low contrast negatives with less film-base fog and loss of film speed. I use Rodinal diluted 1:100 down to 1:200.

It is not practical to use powder based developers for high dilution, since we must to use all powder to prepare a full-strength solution, which has relatively short shelf life. Rodinal however is a liquid concentrate designed for use at 1:25 to 1:50 dilution and has almost unlimited shelf life and is very affordable.

Following are development charts for developing Agfa film in Rodinal (excerpts from Agfa data book).

In Practice..
To establish 'compensating' development, we have to:

• use a very diluted developer.
• use a slow inherently sharp and grainless (almost) film.
• keep strict and consistent development time and agitation program.
• expose for shadows - rating a slow film even slower.
• develop for highlights - experiment and define development time to provide good highlights details.

If using Rodinal, following points must be kept in mind:

• Rodinal is not suited for high temperature - so try to be in range of 18°C to 25°C.
• With Rodinal, and at very low dilution, changes in water hardness can affect the results.

I obtained best results with Agfapan 100 (rated ASA100, exposed ASA80) and Ilford PanF (rated and exposed ASA50). I prefer Agfapan-100 for humans and Pan-F for stills. Sorry that I have no experience with Kodak films since supply of Kodak b&w materials in Israel is very poor.

I develop for 20min at 20°C, inverting once every 5min. It is important to stress out that the degree of agitation is a major factor in the degree of condensation and acutance achieved with highly diluted developers.

Since the film is at rest for a long time, there is a danger of dust particles to adhere to emulsion. To prevent this, cleanliness of the development tank must be kept and the water used for dilution must be filtered and free from particles.

I prefer to use metal tank and spiral. When pouring in the developer I use more than the capacity of the tank to ensure there is minimal air pocket left in the tank.

After development, film is rinsed, fixed and washed according to whatever procedure you prefer.

Results..
It is almost impossible to reproduce the whole tonal range acheivad in a print but I think the folowing two photographs present a good idea of the reachnes of shadow details which can be acheived. Both photographs were shot on Agfapan-100, developed at 1:100 dilution.

Links
I Looked at Agfa site, and found the Agfa b&w Chemicals - Film Processing which contains links to all current Agfa's b&w chemical including RODINAL. There is a link there to a PDF file which includes data-sheets of all Agfas b&w products, but for some reason I did not managed to download it.