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Zone System for Roll Film

Using the Zone System with Roll Film

(Since writing the article below, I've added a post about another way of achieving near-zone system control in 35mm photography. You can read about it here.)

Black and white film photographers will know that we're told to expose for the shadows and develop for the highlights and the Zone System is just a way of quantifying that process. Obviously, if you under-expose the shadows then you'll have nothing more than jet black in the print where there should be some detail. Similarly, if you over-develop then there's a chance the highlights, areas which should be very light but with some detail in the print, will be blocked up on the negative and render as blank white. That's why photographers whose aim is a "fine print" of the highest quality need a way of working all of this out.

Large format photographers (using negatives 5x4 inches in size and upwards) had it relatively easy as they could expose a single sheet of film to ensure shadow detail where it was wanted and then give just the development needed to produce the perfect range of tones to fit onto photographic enlarging paper. With roll film, where all the pictures have to get the same development, this bespoke treatment just isn't possible. So what's the best way to proceed?

Leaving aside development for a moment, measuring shadow areas in a scene and basing exposure on those is still the best way of achieving a good negative. A spot meter is very useful here but if you can approach the subject then it might still be possible to measure shadows accurately. It's important to remember that an exposure meter will try to reproduce whatever you measure as a middle grey zone V value on the negative.

This is valuable as it means that you can choose how dark or light the shadow will register. A "normal" dark shadow might record as zone III on film, two zones lower than a straight meter reading would give. If you take the straight meter reading of a shadow and close down one f-stop (or choose the next higher shutter speed) from that, the tone will record as zone IV on the film. If you stop down two f-stops, you'll get a zone III tone. If you open up one f-stop from the straight meter reading you'll be at a zone VI tone, etc. This is powerful information.

The accepted values for the various zones are these with 0 representing pure black and X pure white:

Say you want to record a statue as a dark object against a light sky but with some detail still visible in it then you take a straight meter reading close-up and close down two f-stops (or go two shutter-speeds higher). You've now got a statue that will record as a zone III on film. Bare in mind that the meter reading must be of the statue only: you can't allow, for example, light from the sky to influence the meter. That, then is how you ensure that you have enough detail in your shadows and that's the first part of the zone system.

Compensating developers
Now we come to development and that's where we run into the hard fact that roll film users can't strictly adhere to the zone system unless they are prepared to have film backs or camera bodies covering a whole range of contrast ratios. Short of that then (don't let me put you off if you're that dedicated!), we have to resort to a compensating developer that stops highlights from getting too dense on the negative.

There are only so many tones that a sheet of enlarging paper can accommodate. Sometimes, in high contrast scenes, a decision to place the shadows on a certain zone will produce a negative with highlights that are too bright to record in the print. Compensating developers help to prevent negative highlights that should have some detail in them from becoming so dense that they record as pure white on enlarging paper.

There are a few ways of achieving compensation in development. One is by using a two-bath such as the one I advocate. The other is to use a highly diluted developer and another is to allow the film to "stand" in the developer for a long time without agitation. Each has its merits but I think the two-bath development process is the best.

Diafine and Tetenal Emofin are possibly the two best-known commercially made two-bath developers and if you don't fancy mixing your own brew - you can get a good formula at the bottom of this page if you do - then I'd start with one of those, following the instructions that come with the packs.

Metering for the shadows to ensure adequate detail where you want it and using a two-bath developer to control highlights will get a roll film user as close to the ideal negative as possible outside of the single negative approach.