Heiland Splitgrade: The enduring lure of chemistry
Twenty years ago the big shake-out in photography started. With auto-everything cameras swamping the market, the need for basic knowledge of the photographic principles disappeared. When cheap and good (well, acceptable) color prints were well established in the mind of the average consumer, many photographers closed the door of their darkroom. Te slide projector too ended someplace in the flea market.
The industry followed this trend diligently and new innovations in the darkroom area became as scarce as a white raven. The supply of papers did shrink considerably, and has only recently stabilized with superb fine art printing papers, both fiber based and resin coated. But the person who now enters the darkroom works in exactly the same way as did our ancestors.
How do you proceed in the darkroom?
You select paper format and enlarger setting. Then you make a number of trial prints to establish the minimum amount of exposure to get the maximum black of the selected paper and grade. Longer exposure will clog up the shadows. Then we finetune our selection of paper grade. We start from experience with Grade 2. But to see how grades 2,5 and 1,5 or even 3 look, we again make trial prints. The industry tells us that we do not have to change exposure when selecting another garde unless it is 4 or 5. This is nonsense. Every grade has its own exposure time for maximum black. So after much trials and many prints later we find an acceptable combination of grade and exposure time. Unless we own a densitometer we must rely on our eyes for judgment, which is not that good as we al know. Zone System workers are in even more trouble, as they are accustomed to work to quite exacting standards to extract the full tonal scale and the correct grey values out of their material. Anyone having followed a Zone System course will recognize the desperation to get a correct N-1 zone strip, or to try to find the correct density for zone VII.
If you have acquainted yourself with as example Ilford Multigrade IV, you would think twice to extent your darkroom technique to Agfa or Kodak or Tetenal or one of the other excellent marques available. Not again, you think, even if these papers have strong advantages for some types of subjects or prints. So a large part of the paper universe will never be experienced,which is a pity indeed.
Then we stumble across the digital darkroom. Scan a negative, let the software do the rest and make a print. Easy and convenient.
Still the 20x30cm print on glossy paper, with its shimmering shadow details, its lucent highlights and sparkling specular whites, its subtly graded grey values haunts our memory.
And an evening spent in the darkroom, alone in the darkness, the pale orange glow in one corner, the fixed working rhythm of developing, fixing,washing, the joy of seeing the latent image glow in the water, it is an experience that has its attractions and fosters reflection.
The basic difference between a digital print (and they are indeed very good these days) and a emulsion based print is the depth of the print. A chemical print has an emulsion layer of 100 microns or more and when exposing/developing the silver halide, suspended in the emulsion we use all silver particles from the very top to the deepest layer. This three dimensional distribution of developed silver gives the chemical print its depth and character. And the negative of course is also emulsion based and so we match two media of three dimensional depth to produce a print.
Digital prints are two dimensional: the digital camera has one layer of ccd sensors and the print also has only one layer of ink. This topic is worth exploring, but now in this article.
The meticulous darkroom worker knows that a small change of exposure time or a small shift of grade will alter the ‘character’ if not the image quality of the print.
But do we have the time to adjust our exposure time by increments of 2 seconds to find the ideal print time. No, we have appointments, emails etc. And while we know that attention to detail is needed to get the best print,w e settle for a very good one, while we would like to have a stunning one.
So a small company in Wetzlar, in the shadows of the famous Leitz buildings, designed a new device that will generate a revolution in the darkroom.
The basics of variable contrast paper and enlarger modules.
VC paper is composed of two different emulsion types in one layer, one sensitive to green light (soft contrast) and one sensitive to blue light (hard contrast). With a yellow and a magenta filter or a mix of both we expose one or both emulsion types for a certain time. The yellow filter blocks out the blue light and so exposes the green sensitive layer. The magenta filter blocks out the green light and so the blue sensitive part is activated. All VC modules use a light box to mix the blue and green colors for one exposure. The specific mix corresponds to the grade 0,1, 2, 3, 4 and 5.
The individual contrast of the green and blue sensitive components are not necessarily the same. When the contrast gradient of one layer differs from the other. it is difficult to get complete control or to predict the results. The exposure is in all cases the same and will result in differences in grey values between grades. It is not easy to match a skin tone in grade 2 to the exact same grey value in grade 3, without changing the overall tonality too.
The Heiland Splitgrade Controller.
The designers call this device a grade management system. The core of the system consists of two parts. One is the VC module which will replace the existing VC module of the enlarger. The module has two separate filters, one for yellow and one for magenta, that are placed into the enlarger light. The paper then is exposed twice, once for the yellow filter and once for the magenta filter, the relative proportions being computed by the system and corresponding to the grade selected. This method of split-filter printing is well-known by fine art printers who need the utmost and precise control over the printing. It provides for better local contrast control, finer differentiation of grey tones and more richness of detail.
As we said before, every paper and every grade within a paper type has its own unique behavior. As both emulsion components are activated simultaneously, the resulting contrast and grey scale and grey tones are the mix of both contrast curves and not predictable. With the split-grade technique, every emulsion component is addressed individually and the exposure can be optimized for every component. So it is possible to dodge and burn locally per component.
You could dodge the shadows during the green exposure and burn them during the blue exposure. Result is a deep black with a high contrast and differentiated dark tones. Normally wehen exposing for deep black the shadows get too dark as the local contrast is too low. The high end part of the characteristic curve is quite often almost horizontal.
The very experienced darkroom worker might accomplish this by training and experimentation. Still it is a matter of many trial runs.
The second and most ingenious part of the system is the controller. The device looks like a timer. But it has a chip built into it, comprising all exposure and contrast data for many current papers. These are not the well-known characteristic curves for every grade as published by the industry (increasingly rare by the way). No, it are the test results of the Heiland people, achieved after many months of testing and densitometer readings to search for every modulation in grade and tonal values and exposure time, related to the split grade technique. This unique database of densitometer readings is the heart of the system.
Attached to the controller is a sensor, that measures ,as any densitometer would, the density of the negative areas. Just move the sensor randomly over the negative area. It will remember the intermediate maximum and minimum values and so will eventually find the true max and min values. If you have more experience or the negative is very challenging, you just locate the min and max values for yourself and measure these. These values then give the density range of the negative. The computer then computes the grade and the exposure time, related to the chosen paper. These three readings (paper type, grade and time) are displayed in the display and could be changed. The user here has full control to change whatever he likes. The software is programmed in such a way, that whatever paper or grade is chosen, maximum black is reached in every situation. Any Zone System worker will remember the laborious work to find the SAT, (minimum exposure to get full black), which changes when the enlargement factor changes. Now it is all programmed in a chip and readily available.
The result looks like this: Contrast range: 1,54 and paper Multigrade IV and time 13.6 seconds and grade 0.5.
The prints were made without any intervention and were dried and then measured on my own densitometer. The black measured a 2.1 and the white a 0.06. Indeed the true and ideal maximum values. This is accomplished without any trial print.
The result is truly a revolution in the darkroom.
Some theory as a sidestep.
Print paper has a maximum black off Dlog 2.1 or a bit higher. Some reach a 2,4. The minimum white is almost always Dlog 0.06. This is a contrast range of Dlog 2.0 or in more familiar terms 1:100. A negative can reach values of 0.0 (unexposed) to 3.5 (fully exposed). This is a contrast range of 1:3000. People now assume that this brightness range can be used when exposing film. Not true. The useful range is much less. Any density above 1,5 will be recorded on paper as pure white. It does not matter how long we expose, it stays undifferentiated white or grey when we expose long enough. So in practise a negative has a density range of Dlog 1.3, that is 1:20!!!
This modest range is expanded on paper to 1:100, whatever the grade. The grey values then will be expanded as well, but for equally divided over the full grey scale.
But not every negative will be perfectly exposed. We have negatives will a shorter range (0.6) or a longer one (1.7) or the overall density is different (over and under exposure). The different grades try to match the negative contrast to the paper contrast. Grades are designated as R50 or R150. Divide by 10 and you have the contrast range. This matching of grades to negative contrast is the basic craft in the darkroom. BUT: a change of grade will change all grey values and they no longer match the original. A skin tone on grade 2 will have a different grey value when printed on grade 3. The split grade method reduces all these changes to a minimum or even can eliminate them.
The test results.
We used five different negatives with a range between 0.7 and 1.9. Also the overall density differed considerably too. The procedure is very simple. The VC module of the Focomat V35 is replaced by the splitgrade module, we connect the controller to the enlarger and to the darkroom light (that will automatically switch off during exposure: very smart) and the sensor to the controller. These is also a footswitch. Negative in the enlarger, find the desired enlargement , set the lens to the working aperture (5.6) and move the sensor over the print area. In the display the contrast value can be read off dynamically. It changes as long as the sensor records higher or lower values. We accepted the result without any change. The display shows selected grade and time. Put the paper in place and expose. Then develop and fix and wash. Some minutes later we have a fully exposed, finely graded print of superior tonality and sparkle. We did this for all negatives and after 15 minutes we had 5 perfect prints without any trial print and without any adjustment. Try this in the digital darkroom! We only used 5 pieces of paper. Some saving in paper, chemicals and time.
Smart is the option to choose between conventional film and chromogenic ones. The latter ones have totally different and difficult characteristic curves. Most of the problems can now be avoided by using the built-in data.
The use of the splitgrade is simplicity itself. Still it produces prints of superior quality which are difficult to match doing it by experience and trial and error. Every negative is densitometrically measured and matched to the grade that gives full tonality and maximum black.
The software is truly a treasure of condensed experience and allows the user not only to cut on trial prints , but also to use more than one paper type without long experimentation. We all know that any paper (Agfa, Ilford, Kodak etc) has its strengths and weaknesses for different types of subjects and moods. To choose freely between them was prohibited as no one would do all the testing for more than one paper type. Now we have a newfound freedom to use every paper to its full potential, matched to our prints and subject matter.
Better prints, less time, less waste of paper, more paper choices. The darkroom is again a joy to be in.
No better buy for the darkroom worker will be found for a long time to come. It might even revive the use of the chemical darkroom. The best prints and the most emotially rewarding are the chemical prints. Chemistry has a strong future. Any photographer who wishes to exploit his/her lenses and equipment, should try this new darkroom instrument. And we can show our digital collegues why a technique more than 150 years old, is worth pursuing and gives results the envy of every observer.