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Saturday, November 29

Negative Thinking - Part Two

Read Part One here if you missed it.

By David M.

Part Two (…or “II” in Zone System language.)

We did previously mention that variable contrast paper (or even, cover your sensitive ears: Photoshop) gives us much more control of the print than when the Zone System was devised. Nevertheless, there might be times when we want or need to change the contrast of our negatives. We might be photographing a dim interior with a bright sunlit scene outside, or making images in a fog, or perhaps recording some faint markings or text that we wish to decode. In the bad old days, recording nuclear bomb tests on film presented extreme difficulties with contrast. This is where expansion and contraction prove useful.
After we’ve established an ordinary development time for ordinary pictures we can also establish times to increase or decrease the contrast of a negative. We mean pictures with ordinary contrast, nor boring pictures, of course. We call ordinary development for ordinary contrast N-0, normal, neither plus nor minus.

Extra development increases contrast and, as you might expect, less development reduces it. Changing agitation would do the same thing, as would a change in temperature or dilution, but it seems like good practice to establish a constant and predictable system and alter one variable at a time. There seems to be no absolute reason not to keep a constant time and vary the others, at least for black and white film. Stand development is an example of adjusted agitation. For extreme minus development I’ve used half-strength developer, but that was to keep the overall time longer than five minutes.

There is a small complication in changing development times. Although the darkest parts of the negative are mostly influenced by changes in development, the thinner parts are slightly affected, too. It can look rather like a small change in film speed. I’ve found that for a one-stop adjustment, I can ignore this, but I may have exceptionally low standards. I also tend to give “a bit more for luck” by rounding my exposures down – a bad habit. Other photographers are more rigorous and compensate by adding a half stop exposure (or whatever they prefer) when they know they will use N-1 reduced development – and so on. All this makes good sense, but for the moment we shall ignore it.

If you’ve read anything about zones, you may remember that Zone Nine is not-quite-paper-white – a very pale grey with no detail but visibly different from the whiteness of the paper; Zone Eight is pale grey with a little bit of visible detail and Zone Seven is light grey with proper details visible in the print. An example often given for Zone Seven is snow with side lighting.

Expansion means moving a particular zone up the scale to the next brightest zone. Some people suggest using Zone Eight as the “pivot point” and some suggest Seven, but as you are calibrating your own system and methods, to make your own prints, I don’t think it’s heresy to suggest that you can choose whatever pivot point suits your own preferences. Let’s take Zone Seven as an example.

In essence, this is a repeat of the way we established our own Normal developing time. In the case of expansion, we expose our test film to Zone Six, which is one stop above the meter reading and find what length of development produces a Zone Seven (two stops over) in a test print. We shall have to use some judgement here, as a textured Zone Seven isn’t quite as easy to identify as Just-not-Black and Not-quite-White.

To make this easier, as you already know both your personal exposure index and your normal developing time, you can expose your standard shed or wall to the meter-reading-plus-two-stops – Zone Seven – and then make a print normally under the standard conditions, to establish what Zone Seven actually looks like in a print made on your enlarger. Then you can use this for reference if you care to take the trouble.

For contraction, we expose the film to Zone Eight, three stops more than the meter’s Zone Five and find how much less development is needed to reduce it to Zone Seven.

I think it’s becoming evident that we are beginning to approach the Densitometer Barrier, where fanatical aliens and ravening beasties lurk, so your trusty guide must leave you. You may prefer to consult trustier guides and better photographers.

But just in case you’ve had enough of peering at test strips, here is a crumb of comfort. Most people find that about twenty percent less development gives minus one contraction (N-1) and about forty percent extra time will give plus one expansion (N+1). Never forget that all this palaver is intended to make your life easier. You probably have better things to do.

You may care to read:
Ansel Adams. The Negative.
John Blakemore. John Blakemore’s Black and White Photography Workshop.
Fred Picker. The Zone VI Workshop.

Googling the "Zone System" will give you about twenty-four million results.

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