PH5LPE Book Test (Part 1)

3.3. The Zone System

Human vision is far superior to any camera, at least at the time of writing, in terms of the range of tones it can encompass within a single field of vision. Certainly cameras are getting much better at ‘seeing’ in the dark, with enhanced clarity at much higher ISO settings; however they can’t cope as well as humans can with both dark and light simultaneously. If you’re still not convinced, look out of a window from the back of a room, so that you can see whatever is on the other side of the window and some of the room simultaneously. This demonstration works best on a dull day with no lights on in the room. You should be able to see the view from the window clearly, and if you look around the room, you should be able to make out details throughout the room, even in the darkest corners. Now compare how your camera sees what you see. If you take a light reading and make an exposure for the view outside the window, the room will be very dark, if not completely devoid of any detail; if you measure and expose for inside the room, the view on the other side of the window will be completely over-exposed, with ‘blown-out’ highlights and no detail. The scenario described here is one of ‘high dynamic range’, and many of you will be familiar with the process of combining several digital images of the same scene made at different exposures. When this process is carried out with restraint and sensible artistic judgement, it can be a very useful tool to extend the tonal range of an image, but sadly many less discerning amateurs and professionals alike use the method rather unnecessarily and over-enthusiastically.

Digital HDR techniques and related software can be seen as an extension of much earlier attempts to achieve greater tonal range in finished photographs. Early photographic emulsions were considerably more sensitive to blue light than to other colours on the spectrum of visible light. This meant that landscape photographs, particularly those made on clear days, had completely blown-out skies as the negatives were much denser in the skies than the foreground, resulting in absence of detail in the (positive) print. Some photographers – most notably Eadweard Muybridge (1830–1904) – made a library of photographs of clouds and skies, which would be layered with a negative where the sky detail was absent in order to make photographs that were closer to human perception.

The Zone System, developed by Ansel Adams and Fred Archer (1889–1963) is essentially a way to visualise how the tones visible in a scene can most effectively be rendered onto the photographic negative. Adams and Archer sought to refine and better manage some of the many variables that affected exposure, such as developer formulae and development times, so that the photographer could more strictly control the contrast and range of tones rendered. They contrived a (slightly confusing!) eleven-point scale of tonal range, ‘0’ being pure black, ‘X’ being pure white.

In reality, both film and digital sensors can render many more ‘zones’ than just eleven. However, what the Zone System scale reminds us is that a light-meter, whether hand-held or built into a camera, is objective. Whether you point it at a dark or a bright subject, it perceives and provides an exposure value at middle grey (Zone V). Therefore, the photographer must decide where in the scene they wish Zone V to be in order to control exposure properly.

This principle may be something you’re already familiar with. However, what the practice of all of the photographers you’ve encountered so far teaches us is that, unlike other areas of photography such as portraiture, where the sitter’s gesture is perhaps more important than the exposure, or a busy street scene where we might excuse the rushed framing of an enthusiastic street photographer, landscape is generally a slower paced, more patient and, in some senses, meditative practice. As such, its viewers and critics are much less forgiving of technical mishaps and expect more from the photographer.

Exercise 6: Zone System in practice

Demonstrate your awareness of the principles of the Zone System and your ability to take accurate light readings by producing three photographs taken in relatively high dynamic range, i.e. contrasting light conditions.

Make sure that your exposure choice renders as much detail as possible in the brightest and darkest areas of the photograph.

Collate your work and any reflections in your learning log.