In my previous article on tilt-shift lenses I talked about tilt and how that affects the plane of focus. It is a pretty great feature, and it is (I believe) behind the increased energy we’re seeing in the press and from camera manufacturers about these lenses. But it’s far from the only trick these little wonders can perform, today we’ll talk about the most basic use of shift (including what the large format guys would call rise and fall), to correct perspective in a photograph.
Perspective control using shift has been a staple of architectural photography for decades. When photographing a building from ground level, perspective causes the top of the building (which is farther from the camera) to show smaller in the image than the bottom. In seeing the real world around us this effect appears quite natural, but in a photograph the effect often makes the building appear as if it were falling over backwards. What we need for the image to “appear” more natural is a way to reduce the perspective-induced distortion of the shape of the building.
This problem isn’t limited to architectural photographers. Nature photographers like myself sometimes run into perspective issues as well. While the lack of straight lines in the natural landscape often obscure the distorting effects of perspective, when I photograph in redwood forests the problem is often inescapable.
With a tilt-shift lens, the solution to “the building problem” is simply to displace (that is, shift) the front element upward relative to the back of the lens, and then recompose the image. (In the example image, perspective is leaving the posts bent in the other direction, so I lower, rather than raise, the front element to compensate.) In the examples, I shifted the lens about four degrees. While far from perfect, the corrected image looks more rectangular, the vertical posts appear vertical in the image.
It should be noted that this sort of perspective correction can be achieved in the digital darkroom as well, using Adobe Photoshop, DXO Optics, or PTLens. In Photoshop the “Lens Distort” filter can be used to correct for this as well as many other types of distortion at the same time, including chromatic aberration, pincushion and barrel distortion. Photoshop’s crop tool also provides perspective correction by use of the perspective checkbox, but I find the filter easier to control. (Unfortunately, Apple Aperture and Adobe Photoshop Lightroom do not yet provide tools for perspective correction.)
There are places for both tools. Digital correction offers a lot of after-the-fact flexibility, and in some cases, particularly with older tilt-shift designs, may produce sharper results. On the other hand, optical correction gives you the ability to “see what you’re shooting” at the time, and with modern optics such as the ::amazon(“B00009XVCD”,”Canon 24/3.5L TS-E II”):: or new Nikon equivalents may produce superior results.
There are far more uses for tilt-shift optics than I’ll be covering here, as well as other challenges and limitations in using them. But, it’s my hope that these introductory articles begin to give you a sense of what all the fuss is about, what abilities tilt-shift lenses bring to the world of 35mm digital SLRs, and whether those abilities are something you can make use of in your own work.