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How to approach a challenging negative
1. Trial print with standard Exposure and Contrast controls. This gives me a working print showing me the White Point and Black Points where I want them. Sometimes everything else will fall in place, but most of the time the Mid Point is skewed (needing gamma adjustment), the shadows are muddy (needing density increase), and the highlights washed out (needing suppression).
2. Trial print with a grade 2.5 (for my darkroom, YMMV), and if the print yields a proper Mid Point, Highlight AND White point, but the shadows and Black Point are weak, the negative demands Split Grade Printing. (Skip to Step 7). Otherwise I'll use the following steps.
How to use the tools
1. Paper flashing. Paper flashing is a technique of exposing the paper to just enough light to NOT produce any visible fogging. You'll flash just below the theshold point. Any more and your White Point depresses and dulls. The result of this technique is to bring out detail (lowering by as much as one Zone) in washed out areas of the picture. Clouds and waterfalls will gain textures and gradients. This is like suppressing the highlights in the Curves dialog.
2. Increased development. Sometimes you can bring a print just to the point of proper exposure, but the Black Point just isn't there. Increasing the development, high rates of agitation and sometimes changing the dilution will be enough to increase density by one Zone in the low levels. Highlight and Mid Point exposure will not change very much. White Point will be affected if your safelight is too bright. This is like moving the Black Point to the right in the Histogram/Gamma dialog. If you underexpose the paper slightly (expose for the highlights) and increase development through time, agitation or developer concentration you can effectively raise the high values.
3. Every brand and model of paper has different response curves. None are linear and how much they shoulder and/or toe will give you minor equivalent control similar to the Curves dialog. The amount of shoulder/toe is also dependent upon the chemistry. For example: Ilford Multigrade in Multigrade Developer has a noticable shoulder (highlight suppression) as compared to Forte Warmtone VC. To achieve a similar shoulder with Forte, I've got to flash the paper. Forte is a good paper if I need to LIFT the highlight curve to add sparkle or "glow" to a picture. (Forte availability is becoming dodgy these days and consistency from batch to batch has been a problem so finding alternatives may be necessary)
4. Localized contrast control. Dodging and Burning are the obvious tools here. But how about spot bleaching? How about local density increase through light rubbing of the print with your fingers during development or "dunk and remove" to suppress development of shadows for extremely high-contrast negatives.
5. Split Grade Printing. Most of the time you can use the above techniques--in fact, with grainy negatives you have to use the above techniques as Split Grade will not work on grainy, high acutance stuff. With Split Grade, you've got to use your test prints as references to know what is and what is not there. I've got a timer designed for Split Grade usage which tells me my effective paper grade. Otherwise, it's purely guess work and requires test prints to keep your sanity.
Split Grade 101
This printing technique uses variable contrast printing papers. These papers have two emulsion layers, each sensitive to a different color light. One layer has a long exposure curve and the other has a very short exposure curve. By exposing the two layers separately we can achieve dramatic results. (It's easy to simulate this in "Photoshop" with two a duplicate layer and aggressive contrast/brightness settings).
The Grade 0 exposure is used to expose the Mid-Point (just slightly underexposed), Highlight and White Point. Paper flashing, dodging and burning may be used where necessary. As a matter of consistency, I always expose the Grade 0 layer first. Completely ignore shadows and Black Point--that will come later. Your only challenge will be with the Mid-Point as this can skew a little once we do the second exposure. Don't try to burn in anything that goes below Zone V (Mid Point). The Grade 0 exposure is the time to work Zone VI-X. Use every trick you need to get this portion of the print correct. Do your test prints without going on with the Grade 5 exposure.
The Grade 5 exposure is used to expose the Black-Point, Shadows and add body to the Mid-Point. You can do a test strip of just the Grade 5 exposure to get in the neighborhood, but otherwise I see little value to doing it without the Grade 0 exposure because once you combine the exposures the second one will almost always be 1/2 stop overexposed. I recommend that you expose *just* enough to set a Black-Point for the print. This will usually leave some areas a little weak, but then you burn in on those areas to add the needed density without the loss of tonal separation. If you overdo the Grade 5 exposure, your mid-tones will go dark and muddy. Otherwise, Increasing the Grade 5 exposure has the same affect as pulling the curve down in the shadows area in the Curves dialog.
There are people who claim that you can Split Grade Print using two similar grade settings, such as Grade 2 and 3. This would give an affective Grade 2.5. This isn't true Split Grade printing, but a technique to achieve mid-grade print results. Since I've gone to a color enlarger head, I don't use this technique.
One parting caution. If you are using a colorhead enlarger, the color mixing controls will not give a solid Grade 5 with most variable-contrast papers, but max out at around 4.5. For Split Grade printing, this normally isn't a problem, but does require some adaptation to your specific darkroom configuration. Each paper responds differently to filtration and may force you to use graded filters instead of the dichromatic filters. An example of this is Perfecta paper which has a slightly different color response than Ilford Multigrade papers.
Ken
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