Minor White Zone System Manual, Fourth printing, copyright 1972 with 19% Gray card
Earlier this month when discussing the Pentax Spotmeter V, I had stated that this was a pretty essential piece of photographic equipment when using the Zone System. I have received some questions about the Zone System and I thought it might be a great idea to expand on what the Zone System is as well as what it is NOT.
First the easy part; the Zone System does not do the thinking for you. As the late Ansel Adams and Minor White stated the Zone System is an enabling technology that allows the photographer to achieve the results that they would like to see in the finish print/image, which in the 1960’s and 70’s is called previsualization. If a photographer wanted certain areas in the photograph print (image) to have some texture/information, it enables them to make an exposure that will exhibit that texture/information in the final print (image).
Adams tried to explain the theory behind the Zone System which became too technical and complicated and it was later that the late Minor White broke it down into the simple terms that belie the basic ideas of the Zone System. To underline the simplicity was White’s famous little yellow Zone System Manual. As you can see of my cover above, the price in 1972 was pretty inexpensive (and I bought it for an even cheaper price at what is now Costco). The one issue with this older book is that it is a perfect bound (glued) book with many of the pages falling out; so it remains togther in my zip-lock plastic baggie.
The Zone System is about understanding light and luminescence (reflected light) such that in bright sunlight, the luminescence range that your eye can detect is broader than the sensitivity of either analog film or a digital sensor. As example for digital capture, if you have a sunny day and your image capture has highlights that are blown out (no texture or complete white-out), then you understand the need for exposure control. The Zone System is essentially the color management system of its day.
What Adams and Fred Archer did in the late 1930’s is evaluate the luminescence scale is in ten steps; from white without texture (Zone 10) to black without texture (Zone 1). The 18% Gray card is Zone 5, right in the middle, which is also the same value your meter, whether digital capture or an analog Spotmeter reads. If you have ever photographed a large area of white snow, but obtain a middle gray (muddy appearing) photograph/image, you may now understand why. Your digital sensor thought that it was metering 19% gray subject and auto exposed to provide that image contrast range.
The real idea behind the Zone System and previsualization is to have an ability to take light meter readings of a proposed composition, understand the luminescence of the brightest area that you wanted to retain some texture (information) as well as the darkest area of texture, then calculate what your exposure should be. For analog black and white film there are some additional processing tricks to either obtain expansions (the subject’s contrast was too limited) or contractions (the subject’s contrast was too great) of the film’s development to attempt to match the intended final darkroom print, as well as some processing tricks to expand or contract the contrast of the printing paper.
The equivalent for digital photography is to look at the histogram of the image capture and then make a determination to either adjust the exposure or anticipate making some post-processing contrast adjustments with software like Photoshop (i.e. curve layer). As stated above, the digital sensors are very sensitive with bright lights and can lose information, even with shooting RAW, so you might error on a slight underexposure to capture the highlight values. For analog black & white film, the opposite is true, there is a potential to lose detail in the dark values of a negative, thus a tendency to slightly overexpose the film to make sure that the dark values are captured by the film.
If you are having issues with your film or digital capture exposures and you are not getting your intended image results (what you had previsualized), then you might want to spend some time understanding the basics behind the Zone System.