Random Camera Blog: Developing High-Contrast Films with POTA

old TechPan, POTA, Nikkormat EL
October 2019

Over the course of the past 20 years, I have been trying to become a better photographer. When I started on this journey, my mentor, William Brudon (1921-2009) was instrumental in extolling the virtues of various films that he used. One of the films that he absolutely loved was Kodak's Technical Pan film. Not only was Bill a photographer, but he was also a well-known natural history and medical illustrator as well as a painter of some wonderful landscapes. For him, Technical Pan was one of those wonder films that could be used for high-contrast black and white reproduction, as well as superb pictorial work and copy work that required a great tonal scale. As a result, I too, realized what a wonderful film TechPan was for landscapes photography. TechPan's drawback was that it was (a) a very slow film of ISO 25, and (b) it required the special Kodak Technidol developer to achieve that wonderful tonal scale. Its advantage is that the film is virtually grainless, making 35mm negatives capable of producing very large prints. It was also available in 120 and 4x5 sheet film. As my supply of TechPan and Technidol developer diminished, I figured that it was the end of working with that film.

However, in the past 8 years, I acquired a supply of TechPan, both in 35mm and a small amount of 120. I had ordered some TD-3 from Photographer's Formulary, and realized that it had a short shelf life, even if unopened. Stand processing in 1/100 Rodinal just didn't do it for me, and I am not a fan of really thin negatives. I had seen POTA listed as a developer to be used with high contrast films, but didn't know much about it. POTA? What the hell is that?

my home-rolled TechPan

Earlier this year, I read up on POTA, and it seemed like a good candidate for developing TechPan as well as other high-contrast films. I had to put that research away for a bit, as we moved from Ann Arbor, MI to just outside Asheville NC in late July. In the past 2 months, I have been developing several high-contrast films with POTA, and am realizing just how good a developer it is.

First of all, what is POTA? According to The Film Developing Cookbook (Anchell & Troop, 1998, Focal Press, 165 pp. ISBN-13: 978-0-240-80277-0), POTA was developed by Martin Levy and the formula published in 1967. The acronym POTA stands for Photo-Optics Technical Area at the Ft. Monmouth military installation where Levy was employed. A weird thing to name a developer after a place, but oh, well. The purpose of POTA was to use high-resolution document films such as Kodak Technical Pan, Agfa Ortho, and Macophot ORT25 as normal photographic films. The why is quite obvious. When properly processed, these ultra fine-grained films can rival large format results using 35mm film.

One thing to keep in mind is that these document films have a limited contrast range, and highlights may be blown out, so they tend to work better in low-contrast situations. Some negatives with one film, Eastman 2378 bears this out. Developers such as Technidol and TD-3 can provide an increased contrast range (up to 12 stops, according to Anchell and Troop), but generally, document films will have impaired highlight rendition in typical daylight scenes.

So, what to do? Anchell and Troop recommend the following developers with document films: XTOL 1:5, POTA, Kodak Technidol-LC, and Photographer's Formulary TD-3. Technidol is no longer manufactured, and TD-3 is also a special developer that has to be ordered. XTOL 1:5 produces thin negatives (at least in my experience). POTA, however, consists of only 2 compounds, and is easy to make yourself. Anchell & Troop state that "POTA-type developers produce exceptionally even density growth over their useful range but have an abrupt shoulder after 8 zones. No further highlight detail is available above that point."

expired TechPan, POTA, Oct. 2019

My original objective was to use POTA to test a bunch of bulk-loaded TechPan that I acquired some time ago. I had planned on hand-rolling it and selling the film after I tested it. It turns out that someone had opened the bulk loader to see what was inside, and that was enough to fog the film through the overlapping sprocket holes, as well as the edges of the frame. Plus, the film expiration date was 1990, so there is some small amount of base fog. I can still use it, but no way that I could sell it like that. Using POTA gave me the urge to test it with other document, high-contrast and ortho films to see how they would fare as traditional pictorial films. I seem to have an inexhaustible supply of Kodak's Kodalith, as well as some other oddball films that the Film Photography Project has made available.

TechPan, shot in 2008, developed in POTA, 2019. Mamiya 645

The formula for POTA does remind me of D-23 in the sense that it is a 2-compound developer.
The components to make 1 liter of POTA:

Sodium Sulfite Anhydrous - 30 g
Phenidone 1.5g
Dissolve the dry chemicals in 750 ml water at 35°C, then add water to make 1 liter. Not all of the Phenidone will dissolve, but don't worry about it.

Use the POTA developer as soon as the temperature cools to 24°C. The developer oxidizes quickly after mixing, and typically it's recommend that you use it within an hour. I recommend that you read Anchell and Troop's book for more information on the chemistry of POTA, and how to modify the formula for longevity and less fogging.

I have plenty of Phenidone and many pounds of Sodium Suflite, so POTA seems to me to be a good alternative to TD-3 and XTOL. I weigh out the dry ingredients for each 1 liter batch and put them in a ziplock bag so that I can mix them when I need them. If you have to order the chemicals, ArtCraft Chemicals Inc. has them, as well as many other raw photo chemicals. 50 g of Phenidone is $12, and 1 lb of Sodium Sulfite is $6.50. That's enough to make 33 liters of developer, which would develop up to 132 rolls of film, for a cost per roll of less than 15 cents. That's pretty damn cheap! Of course, you can use POTA for normal contrast films, but your results may not be optimal.

Anchell and Troop also provide another formula for a low-contrast developer called TDLC-103:

Metol - 1g
Sodium sulfite - 5g
Sodium Bicarbonate (baking soda) - 10g
dissolve to make 1 liter

This doesn't have the problems with Phenidone that POTA has, and I am going to give it a try soon. Anchell and Troop stated that TDLC-103 is more likely to give good results with document films, and as an extreme low contrast developer for normal contrast films. I think development times are 10-15 minutes with minimal agitation - 10 seconds every 3 minutes to suppress highlight development. I am assuming that the development temp is 20° C.

My latest adventure with POTA was developing some long outdated Kodalith Otho Type 3 6556 film. I shot the film in my Nikon F100, rated it at ISO 12, and developed in POTA for 11 minutes. To say I was blown away with my results is an understatement. I did not expect the rich tonal scale that I saw on the negatives. I have never seen such good results with Kodalith before. I am going to shoot some more later this with some different subject matter and see how it goes.