exercise 1.6 – the 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.’

– LPE Coursebook, p.53

fig.1: St Saviour’s Church, Walthamstow

‘The zone system makes use of the basic parameters of exposure and development of the negative to achieve optimum negative quality in reference to the desired results in the print or transparency’

– Ansel Adams, quoted in Schaefer, 1998: p.23

fig.1 was taken on a medium format film camera (with movements – hence the slight Atget-esque  vignetting at the top corners) on one of the mornings a month or so ago when snow fell and lay in London. I was looking west at the time and the light was flat and lacking in contrast. The lightest bit of the framed view was the snow on the roof of the apse, with the overcast sky not far behind. I used a digital camera in spot-metering mode to work out the exposure.

fig.2 and fig.3 are two shot taken with meter’s suggested aperture (shutter speed is constant, the same fraction of a second as the iso setting).  Both are probably around a stop underexposed (ie fig.2 would be better opened up to f4, and the fig.3 a bit above f8) but this still leaves  a range of a little over 2 stops between them, This is plenty of headroom to allow the face of the church to be placed in the middle of the range of zones, set out by Ansel Adams.  Indeed, the sky is not blown in fig.2; indeed, it is possible to adjust the raw output of fig.3  in Lightroom, so that the church ceases to be simply a silhouette:

fig.4: exposure +1 & the shadow areas lifted by another stop

I don’t like the result much (and viewed large there are inky black panes of glass in the windows, that no amount of work will lift into being even the darkest grey) but it gives some idea of how much latitude you can have when working digitally. However, I wanted to make a picture on relatively slow (125 asa) black and white film. I did some calculations based on the two pictures I’d taken coming up with something like this, in my head:

fig.5: thought process (colour) – assembled in photoshop

Here fig.3 has been lifted a stop (f8), fig.2 left as it was (f5.6) apart from the rectangle  at the bottom of the apse, which includes the mid-grey of the bus stop, which has been lifted to the equivalent of f4. The sky to the left of the  church is fine. This section became the basis for the exposure of fig.1.  One thing remained to be done, but it would need to happen later when I was back home.  In colour, there is a fair amount of definition between (say) the yellowish stone of the church and the grey of the bus stop; once the image is desaturated, the distinctions between the stone and the painted metal and the spaces between the bricks are much less distinct. This could be solved by increasing the overall contrast of the image, but this would happen later, rather than in the camera.

fig.6: thought process (b&w) – upping the contrast

If I had been dealing with a single image, I could have increased the contrast by increasing the time the sheet film spent in the developing solution; here though there were another 11 images on a single roll, all of which would have benefited with different treatments. I also could have printed the image on a paper graded for higher contrast, but  – while I have the wherewithal to develop negatives, I don’t have a printing darkroom. Instead, when scanning the negative, I adjusted the output settings to include as many differentiations between black (0) and white (255) as possible (roughly equivalent to push processing) and then increased the contrast further in Lightroom (printing on more contrasty paper). The red rectangle in fig.6 encloses an area without the Lightroom adjustment; the surrounding, f4-equivalent rectangle shows the effect of increasing the contrast.

fig.1 – shows the cumulative effect of all this thinking: a 1/125th” exposure at f4 (or rather, to increase the depth of field and the sharpness of the stonework a 1/8″ exposure at f16) on Ilford FP4+ film. It works quite well I think, but it would be better if I could have reduced the need for moving the lens to get this very tall building into a single shot by either moving backwards (prevented by a wall, and anyway the intruding branches of the trees on this side of the road would have got even more in the way) or by using a wider lens…

‘The zone system was a solution for inadequacies in the basic [ie analogue, black and white – SC note] photographic process – inadequacies that I believe are being tackled digitally in quite different ways.This is not what you will read by zone system enthusiasts, but that’s because of the mistaken belief that you can go on adapting old techniques to new circumstances.’

– Freeman: 118

The inadequacies of traditional black and white film are products of the chemical process itself: the chemical emulsion responds to a narrower set of light conditions than the human eye (ie its dynamic range is narrower) and, because the energy contained by light is what causes the basic chemical reaction central to traditional photography, it reacts very poorly indeed to being underexposed. Underexposure leads to flat, black areas that lack detail in chemical photographs; at the other end of the exposure scale, film does better, recording detail even when it is quite badly overexposed. Underexposure is therefore the cardinal sin of film photography.

With digital, this situation is reversed: digital sensors record things that we cannot see in darkness (and .raw files store the information so we can access it); but unlike analogue technologies, overloaded sensors do not produce distortion (in audio terms, think of Keith Richards’ fuzzed guitar riff for Satisfaction), instead they clip and what should be a curved wave gets squared off at the high points. This is not pleasant either visually or aurally. So, the cardinal sin in digital photography is to overexpose your image and blow the highlights; it may be possible to get detail in shadows, care must still be taken not to create white holes in the brighter areas of the image. Software makes this easier, with sliders for raising the black point and lightening the shadow areas pretty much standard. As was shown in fig.4, a lot can be done with even the most unpromising material.

Because of this, I generally have my digital cameras set to underexpose by 1/3 of a stop and – if the scene is particularly contrasty – to include more of the brightest area of the image in the area of the frame where the desired exposure is being measured. In fig.7, I tilted the camera up to read more of the sky and then raised the shadows out of blackness in Lightroom. A corresponding reduction to the highlights brought back a lot of variation in the clouds, as well as some of the sunset orange. The spire is of course, St Saviours’ again; you can make out the three vertical windows quite clearly, despite the church being fully silhouetted by the setting sun.

fig.7 – looking west, late afternoon

fig.7 is all about contrast; fig.8 has a much more even need to show detail. Again, I included more of the sky in the metering spot than is there in the final framed image, and then worked the software to get detail on the walls of the flooded underpass. The sky is not quite pure white. The picture is about as extreme in contrast terms as I like to go and the rainbow painted on the concrete is beginning to get a bit too pronounced. I’ve reduced both the vividness of the colour and its saturation, and I could do more, but then the natural greens of the foliage would start to look too anaemic.

fig.8 looking north, early afternoon

Having reached this point, I could either start working with masks in Photoshop proper or I could have shot a number of shots, with different exposures and process the image(s) as HDR (blending different areas so the whole image – in theory at least – more accurately represents the range of tones viewed by the human eye. However, I’m not a great fan of HDR as it all tends to go a bit painterly even when done quite subtly. Generally, if a scene is lit by too contrasty a light, I’ll come back on a day when it is all a bit more subdued (which is generally easy beneath Northern Europe’s flat winter cloud) or at a time of day when the light is coming from the opposite direction to my viewpoint – looking West in the morning, or East in the afternoon…


Reference:
  • Freeman, M. (2011) The Photographer’s exposure field guide. Lewes: Ilex Press Ltd.
  • Shaefer, J.P. (1998) The Ansel Adams guide, book 2: basic techniques of photography. Boston: Little Brown and Company

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s