Vancouver test site
In the spring of 1983, I lived in a basement room in a communal house, in the South Cambie neighbourhood of Vancouver, B.C. — the third house I’d shared with fellow Mountain Equipment Co-op employees. Good times! Lots of skiing and climbing adventures. And the dance parties. Meanwhile, I was shooting product for MEC’s biannual catalogue. The image above represents my “office.” The rest of the basement was taken up with a makeshift studio.
The purchase of a Mamiyaflex medium-format camera inspired me to study film exposure in earnest, and launched the project now called Eighties Vancouver. The first roll of film I shot with that camera included the test shot reproduced above, following Ansel Adams’ Zone System conventions.
Zoning in on correct exposure
The first thing any photographer should understand, in order to make informed decisions about exposure, is that the photographic exposure meter, hand-held or in-camera, is calibrated to “middle,” or 18%, grey. That is to say, a particular subject, of any luminance, measured with a meter is assumed by the device to be 18% grey.
Which is why an isolated or spot reading of, say, a white horse against a grey barn will, at the end of the day, result in a grey horse, while a spot reading of a black horse against the same background produces … a grey horse. In the former situation then, assuming one wanted to reproduce the fidelity of the original subject, the horse, one would overexpose. In the second case, underexpose. But how do we decide how much to deviate from the norm?
The second thing to recognize is that in-camera meters are reflective. They average the luminance of a scene. (Yes, modern cameras use advanced algorithmic technology to add to this basic reading. More on that later). In the former example, a reflective meter would try to compute the exposure from the variety of reflective surfaces in the scene — the barn and the horse. Since most metres are centre-weighted, the problem outlined above would result in a less-than-ideal exposure. Imagine the problems this method introduces when photographing snowy scenes, or shooting at night. An incident meter reading, which measures the light source (e.g. the sun) is often more accurate where variances in subject color or reflectance are most likely to throw off a reflective meter. But where incident readings are impractical, a handheld 1-degree spot meter (visible in the above photo, in the lower-left corner) allows the most selective measurement of distant and small areas in complex scenes.
The range of luminance from the brightest white in a scene to the darkest black is called dynamic range. Dynamic range is measured in Exposure Value (EV) or ‘stops’. The human eye is capable of perceiving a total light range of approximately 24 full f/stops. Properly developed film has a range of 12 EV. The best digital cameras can record about 14 EV. Digital Raw files add about an extra stop. Prints can reproduce only 6.6 stops.
The Zone System
Seventy years ago, California photographer Ansel Adams, in collaboration with portrait photographer Fred R. Archer, created the Zone System to standardize photographic procedure — through exposure, development of the negative and printing on photographic paper — to accurately render the photographer’s vision.
By creating a negative that affords the greatest range of opportunities for interpretation — Adams likened the negative to a musical score, the print to its orchestral performance — the photographer, or maestro, has in his hands an “arrangement” worthy of committing to paper.
In Chapter 4 of The Negative — Book 2 in his Photography Series — Adams explains, “The Zone System allows us to relate various luminance’s of a subject with the gray values from black to white that we visualize to represent each one in the final image.
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“In Zone System terms, we say that we first placed the luminance of of the middle-gray [18%] subject area on Zone V of the exposure scale, and then the other luminance’s fell on the other zones. …. We place one luminance on a specific exposure zone and then observe where other luminance’s fall.
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“Thus the essential rule: we can place any one luminance value on any zone of the exposure scale, and doing so will determine the camera exposure. We can then read other luminance’s of the subject, and these will fall elsewhere on the scale of zones, with each one-stop or 1:2 luminance change representing a one-zone difference.”
The Zone System was developed, so to speak, for use with view-cameras and sheet film, where each exposure could be calibrated from the point of exposure to optimize choices at the final expression: the print (the final book in Adams’ trilogy). Roll film, with many exposures developed together, cannot be controlled to the same degree, unless the whole film is exposed in exactly the same conditions and developed accordingly. However, Zone System theory can still be adapted to roll film by careful exposure and development.
The idea was/is to take advantage of as much of a film’s characteristic curve — an exposure range of around 12 stops — by correct exposure, optimal development based on testing, and artistic pre-visualization of where the photographer wants tones to lay in the final image, thereby creating the kind of atmosphere he wants to evoke.
This procedure may sound confusing and laborious, but establishing the relationships between luminance in different areas of the subject enables us to anticipate more-or-less exactly how various parts of the final image will look. By understanding Zone System theory, I believe we can benefit from its controls, whether we expose film or a digital sensor.
A Pentax spot meter was used to measure Still Life With Typewriter (above) and, as mentioned, is visible in the lower right quadrant of the image. The sketch below, made at the time, notes luminance measurements, recorded in EV. Frame #11, exposed by averaging, with EV4 placed on zone IV, was overexposed. The successful exposure placed the shadow area EV4 (right side of typewriter body) on zone II. Both #10 and #12 print well.
As noted above, modern cameras use sophisticated algorithms, such as “matrix metering” to optimize reflected exposure, but this post intends to encourage the photographer to analyze what’s in front of her camera to visualize what she’d like to see in the final expression — whether intended for an LCD screen or fine art print.
Today we also have instant feedback, via our digital camera’s histogram, to examine distribution of tones in an image. Where a luminance falls outside the range of our camera’s sensor (A digital camera can record around 8-12 stops. The dynamic range of Nikon’s D800 has been measured at 14.4 EV at ISO 100), we might employ high dynamic range (HDR) technique combining several exposures, which, used judiciously, may be the 21st century answer to the Zone System —at least when photographing relatively static subjects.
Graduated neutral-density filters may also be used to control exposure selectively, especially when using short-scale reversal (slide) film as well as with any high-contrast scene. These filters, as indicated by their name, are neutral in colour (at least the best ones are) ranging from clear on one half to various degrees of exposure control (-stops). These are useful in scenes where, say, the brightness of the sky compared to desired detail in the landscape exceeds the exposure range of film or sensor. The darker area of the filter is positioned over the sky. I find that, most often, the flexibility of RAW files and post-processing techniques replace the need for GND filters.
One stop is a two-times increase or decrease of light exposure. Adjusting aperture, shutter speed, or ISO controls by one stop results either in twice more or twice less light admitted to film or sensor.
With our film exposed correctly for the luminance range of the scene, we proceed to development.
Normal development for a given film is determined, ideally, by testing and densitometer reading of the negative, but my experience has been that manufacturers recommendations, followed to the letter, are a very good guide.
An exposure made in contrasty conditions generally calls for a contraction of development (say, N−1), whereas a shot made under dull skies, or a short tonal scale subject, is spread out by extended development (N+1). Adams’ famous Clearing Winter Storm, Yosemite National Park negative was processed in this way (though he lamented not extending development further, as the negative demanded Grade 3 (contrasty) paper.
For N−1 or N+1 development, try a time variation of 25% as a starting point.
As I said, a spot meter is the best choice to fully exploit the controls of the Zone System. Its 1 degree measurement angle can zero-in on small areas to precisely determine luminance. A spot meter, with comparative EV readings and zone scale is really crucial to precise Zone System metering.
In digital terms, “developing” has become all but instant in-camera, but we can perhaps compare the analog process of exacting Zone System development to modern computer manipulations, where we process RAW files and use post-processing software and techniques to perfect files for printing. In that sense, the digital “negative,” remains the basis for a successful final print.
Wet printing (using Adams’ metaphor, the “conducting” of the musical score) used combinations of paper contrast grades (or Ilford’s “Multigrade” papers, controlled by enlarger filters) chemical developers, selective bleaching (with noxious potassium ferricyanide), and toners (e.g. gold, sepia, selenium — equally poisonous processes) to achieve the desired chiaroscuro of tones. Masters of these photographic techniques gave us prints that offer a lifetime of inspiration.
Today’s digital printer — less alchemist than technologist — is concerned with monitor and paper profiles, colour gamut (gamut originally a reference to musical pitch), RIP software, and post-processing options.
In digital printing, it goes without saying that monitor calibration is key to producing prints faithful to on-screen editing. I use the ColorMunki system.
Inkjet printers, once useless for serious photographic reproduction due to fading inks, now challenge the most long-lasting vintage printing processes for archival permanence, using extremely stable and vibrant inks, such as Epson’s High Dynamic Range (HDR) UltraChrome® pigments.
To the delight of paper fetishists like myself, paper manufacturers like Ilford, Canson, Hahnemühle, and Legion/Moab have responded to the digital printing era with an panoply of products, from matte to satin to gloss surfaces, from alpha cellulose (buffered, lignin-free) to 100% acid-free rag papers.
Perhaps nothing can eclipse the jewel-like quality of a fine silver or palladium print, yet the latest inkjet printers use wide gamut inks and “Micro Piezo” print heads to achieve amazingly subtle gradation of tones. Epson’s Pro 900 Series, for instance, use 11 inks (4 dedicated to greyscale: Photo Black, Matte Black, Light Black, and Light Light Black), employing 3 of the latter at any one time, depending on paper surface. Epson software includes an “Advanced Black & White (ABW) mode, with built-in “toning” adjustments.
This 2-time cancer survivor does not miss messing with darkroom chemicals.
In the digital zone
“I believe the electronic image will be the next major advance. Such systems will have their own inherent and inescapable structural characteristics, and the artist and functional practitioner will again strive to comprehend and control them.” ~ Ansel Adams
Is the Zone system applicable to digital photography? I believe it is. By contemplating its goals and understanding the technical limitations of sensors (like film) and techniques of metering, we can gain a deeper understanding of the photographic process, better to exploit its qualities in service of our ideas.
In short, the Zone System objective is to properly expose the shadows so that there is still printable detail (transparent area of a negative). Accordingly, the perennial dictum was “expose for the shadows; develop for the highlights.” In digital terms, we now say “expose to the right (ETTR),” referring to the histogram associated with an image. We slightly overexpose the image in order to assure correct density in shadow areas, without clipping the highlights. In theory, this also results in less noise in the shadows and smoother tonal gradations.
A full discussion of digital/analog comparison is beyond the scope of this already wordy essay. I recommend the linked article ← for further reading.
The key to controlling exposure and expanding your creative options during image production rests on these foundations:
- Visualizing at the time of exposure how you might ultimately interpret the subject.
- Exploit the dynamic range of the subject and the film or sensor’s ability/limitations to record a tonal range likely to create the most versatile negative or digital file — ideally with no “clipped” shadows or highlights.
- In the darkroom or during digital post-production (“Lightroom” as Adobe so cleverly branded it) exploit the recorded tonal scale to create an evocative image worthy of all the thought you put into the original exposure.
Photographic exposure is based on a meter reading — made either in-camera or with a hand held meter. Master metering, and you’re part way to technical photographic proficiency. Now you just have to find your Moonrise over Hernandez or Clearing Winter Storm.
Analog tools visible in Still Life With Typewriter: “Spotone” spotting inks, used to retouch prints (left side, to right of plant and pen jar); Kodak Professional Photoguide (left lower corner); Pentax Spot meter & case (right lower corner); Flash bracket (between meter and lamp base) Ansel Adams’ book The Negative (right of lamp, with meter box on top) Incidentally, the
computer typewriter is an electric Olivetti “Editor 2.”