Taming Wide-Angle Distortion
In a previous Tip of the Week, I encouraged using wide-angle to add foreground. The example in that previous entry was a scene from nature, which (fortuitously) masked many tell-tale signs of the optical distortion often associated with wide angle. In this scene, we have man-made structures which, if we’re not careful, can easily distract the viewer’s attention because they are bending and/or leaning, and we don’t expect that of buildings or towers (unless we live in Pisa).
My first choice of lens for this situation was either a 24mm or a 28mm wide angle (for a 35mm camera). Unexpectedly, I didn’t have the use of either of those lenses (a subject for a future story) and so I was forced to use the only working wide-angle lens in my bag: a 20mm f2.8 super wide-angle giving 90° of view. I loved this lens for all the foreground it provided for me in numerous nature shots, but the towers and buildings in this scene were really vulnerable to dark side of super wide-angle: barrel distortion. Knowing that the distortion gets worse the farther your lines are from the center, I was careful to place the horizon close to the middle vertically, and the tower and building close to the middle horizontally. Of course, placing things in the middle of the image tends to make for boring composition. After the image was committed to film, I used cropping to place features in better positions (à la Rule of Thirds). In general, I try to not be too dogmatic about following the Rule of Thirds because it can easily become too strong of a pattern. However, in this case, I moved the horizon up from the center, strengthening the composition while giving a very expansive feel to the field of tulips. To some extent, the cropping gave me the angular view of the 24mm or 28mm lens I had first wanted to use, but not quite. First, to get this view in a less wide-angle lens, I would have had to aim the lens in a slightly different angle, and that would have put the horizon off center, which would have bent it. Second, there is a desirable perspective effect created by a super wide-angle lens that causes nearby objects to be much larger than the far-away objects (the foreground tulips appear larger than the tower or building in the background); some of that effect would have been lost with a less wide-angle lens.
This shot was taken 22 years ago. Today, with digital tools at our disposal, we can correct for barrel distortion very easily on the computer. In this scene, some of the barrel distortion (particularly in the field of tulips) is desirable — we don’t want to “correct” for it. The key to achieving this effect is to tame the wide-angle distortion by placing straight lines near the middle and then cropping the captured image to produce more aesthetic composition.
Tip of the Week
2007.02.26
