Exercises in Visualization

The outing where I was able to capture some neat underpass graffiti was originally intended to take advantage of clear cold weather for getting a shot of the University of Illinois’ power plant in full steam.

The previous day had much the same weather but I was limited to scouting the area for a good location, which gave me time to visualize my image. I wanted a strong monochrome rendering of the scene, and thought of Ansel Adams’ visualization of his famous photograph Monolith, The Face of Half Dome, as described in Examples: The Making of 40 Photographs:

I saw the photograph as a brooding form, with deep shadows and a distant sharp white peak against a dark sky. The only way I could represent this adequately was to use my deep red Wratten No. 29 filter, hoping it would produce the effect I visualized. (p. 4)

In the same way, I wanted the stacks and steam to stand out against a dark sky, while the values of the rest of the building could fall where they may, as long as they were legible. The old Main Line of Mid-America runs right next to the plant; I realized that the top of its embankment was the best place to put my camera.

Not being sure of the optimal focal length, I used my 18-105mm Nikkor, my most versatile lens. f/8 provided adequate depth of field. Without camera movements to manage convergence, I knew I’d have to tilt up and correct perspective in post, and frame just a touch loosely to allow an accurate crop. I exposed to the right and made several exposures with different shapes of steam plumes.

Lightroom’s B&W converter is like Channel Mixer on steroids; it allows the user to control the relative contributions of eight colors to the values of the final image. For this image I took the automatic levels and severely decreased the contribution of blue, darkening sky and shadows without appreciably affecting other values. It took a little more work to find the right amount of perspective correction, and not all parallel lines are strictly parallel even in the final rendering; the stacks are appreciably straight, however, which establishes the necessary orientation and sense of height.

I could have further darkened the sky by using a polarizing filter, but did not think of it while shooting; in any case, it is probably better to capture optimal data and tweak the relative color luminances later, rather than polarize and bake-in relative tonalities I cannot undo.

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