The state of the art in BW photography (2005)
It is unlikely that we will see new black & white emulsions in the near future. Perhaps once the digital tsunami waves have calmed down, and there is a revival of the BW niche, the surviving companies will exploit the highly advanced crystal technology, that has been developed since 1990, but shelved because of the digital phalanx. For now we have to do with the current materials. That is not a punishment, to be honest, as the quality of today's film emulsions is much higher than can be used in every day situations.
To return briefly to the super high resolution hype. There are claims made by the Zeiss marketing persons, based presumably on the writings of the Gigabit company that the Agfa Copex film is capable of resolving 700 linepairs/mm and that the Zeiss lenses can easily resolve 400 lp/mm with this film. I repeat my statement, based on extensive research into the capability of the high-resolution films (Agfa Copex, Kodak Technical Pan, Agfa Ortho, Agfa APX25), that it is impossible to record more than 150 to 175 lp/mm on film and that only part of this resolution can be transported to the print. Secondly, even if it were possible to resolve this fine pattern, it has no relevance to the true optical performance of a lens. In this respect the Zeiss claim is doubly false.
My position has been supported in an unexpected way. After describing my position on my website, I got several emails from the Head of the Zeiss optical lab, who in essence said that it is not possible to infer from resolution figures anything meaningful about the quality of a lens and that even if 400 lp/mm could be possible, it has no relevance in the current practice of bw-photograpy.
If we are working with 35mm negatives and print these negatives in our darkroom, it becomes quite impractical and at least quite cumbersome to create prints larger than 30 x 40 cm, 40 x 50cm being the absolute limit. If you really want these big formats and even more, then it is best to buy a high-end scanner and a large A2 digital printer. You may loose some intrinsic quality, but it is much easier to produce large prints. Chemically produced prints are limited to the sizes A4 and A3. I see no problem here, as these formats deliver a picture quality that is full of tonality and brittle sharp. When working with these formats, we are enlarging our negatives 10 to 15 times. The maximum resolution your unaided eye can detect is about 6 to 10 lp/mm. This is indeed the rich detail we want in our prints. The print emulsions can handle more than 20 lp/mm so that is no problem at all. Setting our standards extremely high with 10 lp/mm on the enlarged print, the negative needs to record 150 lp/mm and that is exact what is possible with today's high class optics and films.
In the literature on can read that the limit of resolution for a lens is 40 lp/mm with good contrast (above 50%). I would like to set the limit at 100 lp/mm to have some reserve power when needed. This limit is already a formidable hurdle for most lenses, for solid state imagery and for silver-halide imagery
Reviewing the landscape of films for BW photography, we can make a classification in four types: (a) the slow speed microfilms, tweaked by special developers for continuous tone work, now only Agfa Copex and Kodak Imagelink HQ (b) the slow speed thin films of Adox origin, made in what used to be Eastern Europe: The Maco UP 25, the EFke 25 and its siblings (c) the classical film emulsions from the seventies, like Ilford FP4 plus and Kodak Plus-X Pan (d) the modern emulsions based on T-grain or core shell technology, like Kodak T-Max100 and Ilford Delta100pro
A short history and description of film emulsions
Most films in the past were of a two-layer type to get exposure latitude and speed. The grain was made from hexagonal crystals with different sizes, but speed and sharpness were limited. The first real progress came around 1950 when Adox introduced the famous thin film KB14. Its main properties were very thin layer and evenly distributed fine grain. These films were difficult to tame for contrast and sharpness and new techniques had to be invented to get god results with these films. The current crop of Adox related films have the same properties and difficulties. Once mastered, they give excellent sharpness and good tonality, but in my experience the smoothness of tones is lacking. But the grain is fine with a hint of coarseness, that give images a kind of gritty look, like Tri-X but with much finer grain.
Fine grain and thin layers
Thin layers and finely distributed grain are the properties of the microfilms too and to get pictorial results the films must be substantially downgraded in sensitivity and the developer must have a very weak activity to create a semblance of an S-shaped contrast curve. The Copex as example has an inherent speed of ISO320 that is forced down to about ISO10-12 for normal photography. These films are extremely fine grained but sharpness is not as pronounced as with the classical emulsions. The myth that fine grain and sharpness or detail definition go hand in hand is difficult to get rid of, but when working in BW photography, we cannot allow ourselves to make choices on myth.
The major breakthrough was made by Kodak with Panatomic-X, when they introduced a film with larger crystal sizes, but different shape and arranged in such a way that scatter in the negative during enlargement was reduced. We call this the acutance effect. The big and only problem with creating high quality prints is the existence of scatter and irradiation in the negative emulsion. A very fine-grained emulsion will scatter the light quite a bit and therefore edges of fine detail are softened. The quest for definition is not through the finest grain, but through the best shaped grain!
At this moment in history the tabular shaped crystals enter the stage. Kodak introduced these shapes into BW photography after the success with colour neg films in the famous VR series. Acutance was lost, but Kodak assumed that grain was sufficiently fine and the grain clumbs evenly distributed to offset this loss. An elaborate surface shape of the crystals reduced scatter. Ilford in its turn based the new core shell crystals on the properties of BW emulsions like the PanFPlus and FP4Plus. Here acutance was still in place, but now the clumping of the crystals was controlled to give sharply defined edges. As with the original Adox emulsions, it takes some time to get acquainted with the new Ilford or Kodak films. Contrast control is often difficult, as it was with Adox films, and grain and sharpness are close to that of the microfilms.
The embarrasse de riche
We should proceed in two stages: first the film and then the developer. Never try to select a combination to start with and then do comparisons with other combos. You will end up very confused. Robert Parker, the best and famous wine connoisseur of America, can judge a wine in one minute, but we lesser mortals have to spend at least half a year before we can judge a film/developer combination fully and if we combine this combination with the fine qualities of current Leica lenses, we may spend a year or more before we know what we are talking about. You should forget the Adox derivates: extensive comparisons have shown that they do not perform in the same league as the Tmax and Delta films: grain is not better, sharpness often less good and tonality lower. Also forget the PanFPlus. The Delta100 is better in all respects expect fineness of grain. The definition of fine detail however is quite lower and this will lower the impact of the print. With developers like Paterson FX39 the film is capable of excellent results however. A film for aficionados that are seeking a specific print quality based on smoothness of grain in large even toned areas.
The classical emulsions like Plus-X and FP4Plus are characterised by the acutance effect, excellent tonality but a kind of subspace granularity, that becomes evident at magnifications above 8x. Resolution is also lower, reducing the recording of very fine subtle details and tonal changes. We may remark that even at 8x a film like Tri-X exhibits great sharpness and punch. The eye is quite forgiving in not being able to see very fine detail with good clarity. If you prefer full negative prints on A4 format, these classical emulsions are a better choice than the Adox films or the microfilms.
The TMax and Delta films allow for higher enlargements and superior rendition of very fine detail. Grain is for most purposes as fine as that of microfilms and definition is excellent. These two films in the ISO100 category are the best choices for high quality imagery. It is best to expose both at EI80 and not at EI100 to get a somewhat better shadow definition. These films are best for outstanding image quality at 8 to 12 times enlargement on A4. At 15 times enlargement some caution is needed to suppress the grain impression in extended areas of even density. Here the microfilms have a definite advantage.
The choice between TMax or Delta is simple: Delta has sharper and larger grain and gives outstanding definition and clarity of detail, but it is best when there is much fine detail to record. If you wish to have smooth grain in white and grey areas of some extension, wit a bit loss of detail definition, the TMax is the best choice. The differences are small and both films deliver excellent results.
When do we want to use the complicated microfilms? If you use a tripod or a studio flash and want to record every possible detail the lens can record, a microfilm might be the best choice. When exposed and developed correctly, such a film can give extremely clear definition of fine detail and good sharpness of major subject outlines, but not acutance. The developer is crucial here.
For microfilms I have only one choice: Kodak Imagelink HQ and dedicated Spur developer. The Copex alternative has larger grain and less sensitivity. The Gigabit solution has to be avoided as it gives a low contrast and thin negative. Resolution is quite good at more than 100 lp/mm. The Imagelink alternative has finer grain, higher speed and excellent definition of fine details. The density of the negative is better and one can use a normal 2 or 3 grade. The Copex/Gigabit is best printed at grade 4 or 5, losing smoothness of gradation. Compared to TMax or Delta, the sparkle in the print is subdued.
For TMax and Delta I use either Amaloco chemicals or Spur chemicals. The new Spur SD 2525 is a two-part developer that brings outstanding smoothness of grain and sharpness. See my examples. Both types of developers are highly diluted ones and this is the secret of the image quality. Exposure must be on the brink of over exposure to ensure shadow detail and development times as short as possible to give good highlight separation. I have no intention to be specific here with times and film handling. One needs to do some experimentation to get the results that are pleasing.
Having selected a type of film, one should start to experiment with developers, but with some caution. Developers are more alike than one expects. Good average results you get with XTol, but if you need to expand in one direction or the other (granularity or definition) specialist developers are required. I will go in the direction of definition as this is where Leica lenses excel, but others might select the grain approach.
My route is this:
Select TMax or Delta in the ISO100 class or preferably use both. Experiment with a standard developer like XTol or use Paterson FX39, AM50, AM74 or Spur HRX-2 or SD2525 as a start. If you are a dedicated sharpness addict go for Rodinal or Neofin Blue. Experiments extend to changing ISO rating, enlargement factors and times of development and exposure technique. Also use prints at A4 and A3 size. Relate subject to result. An industrial landscape may require different parameters than a subtle nude. Happy? Fine, stay with your results. Focus more on film than on developer. Fine tune exposure technique and camera technique (shutter speed and accurate focusing and depth of field settings). If subtle changes are needed, try to change within the selected options. Do not change film or developer too quickly. If not happy: go for microfilms or and this is surprising ISO400 films of modern character: Tmax400 and Delta400Pro. Results may be surprising.