Tilt-and-shift lenses

Imagine being able to take a lens in your hand and move it around until it gives you precisely the angle and view that you want, including the depth of field and emphasis on various foreground and background elements. This is essentially what the controls on tilt-and-shift lenses allow you to adjust — you can change various geometric optical factors common to and frustrating with other lenses. Have you ever tried to take a photo of a building and been frustrated by converging edges of walls that make it look angled instead of straight? Tilt-and-shift lenses correct that effect, working to realign images by changing trapezoidal angles on a focal plane, and, in some cases, virtually eliminating geometric aberrations and convergence — which is why architects, in particular, love them. The lenses use a very special, precision, floating optical system.

While often used in wide-angle types of shots, tilt-and-shift lenses actually come in a variety of focal lengths. Canon’s are available in three focal lengths:

  • TS-E 24mm f/3.5L
  • TS-E 45mm f/2.8
  • TS-E 90mm f/2.8

The Canon TS-E 24mm f/3.5L tilt-and-shift lens. Note the tilt knob on the top of the lens and the shift knob on the side.

Canon tilt-and-shift lenses only offer manual focusing (which is why they do not feature an EF in their names) and you can tilt the axis of the lens’s focal plane as well as shift perpendicular to the axis using small knobs on the lens (see 6-25). Essentially, they carry the simple effect you can get by tilting a wide-angle lens, eliminating the bending of the center line to a much greater extent to affect a variety of lines throughout the image. For example, you could straighten vertical lines on the side of a building, effectively eliminating convergence, or you could flatten a horizontal line across the image, such as the one of the fencers shown earlier in figure 6-15.

Tilt-and-shift lenses also let you play with the depth of field in an image, extending it by changing how the lens is focusing so that even with a wide aperture, you can adjust the axis of focus to various nonstandard elements of the photo.

Why would you use a tilt-and-shift lens? You would if you’re trying to take a photo of a house or building, for example, and you want to get as much of it in the image as possible without suffering from the bent edges typical in a wide-angle shot that would get cut out in image editing. Or you may have a straight element in one corner of an image — say, for example, a street sign — that you want to appear straight while a building or other element in another part of the image needs to remain equally undistorted. Normally this would take layering in Photoshop or another program in order to overcome the effect; with tilt-and-shift, the original image can be corrected when it’s shot.


Tip

For an excellent interactive description of tilt-and-shift lenses, go to the Canon Professional Network online at Canon Europe.

Category: Science of Lenses

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