I sacrificed my infrared camera last week so that I could get two of Canon's tilt/shift lenses, the 90mm f/2.8 TS-E and the 24mm f/3.5L TS-E. I really wanted the 90 TS-E for serious flower photography (where tilting the focal plane would come in handy). The 24mm TS-E will be interesting to play with for shooting interiors and architecture. Its close focusing ability (down to a ft.) also makes it an interesting lens for exaggerated perspective.
I spent a couple of hours playing with both lenses and getting used to the tilt and shift operations. Both of my lenses had already been modified so that the tilt and shift are on the same axis (they come from the factory in opposite axes). In playing around I was able to immediately see how this is useful. I found myself composing the shot un-tilted. Once you apply some tilt, the image shifts on the same axis, requiring a little bit of shift to restore composition.
I have a lot of experimenting to do in order to really get the hang of these lenses. They definitely benefit from tripod mounting and live view is a real boon for using these kinds of lenses. Both lenses seem to be great performers. The 90 TS-E is wickedly sharp even wide open and though the 24 isn't quite as impressive but its no slouch either.
The top image is an animated GIF switching alternating un-tilted and tilted images of my toy car with the 24 TS-E. The tilted version is the one where both the headlight and the windshield are in focus. The left image is with the 90 TS-E, the tilted image is the one where more buttons on the phone are in focus.
Technical Specs: Canon 1D3, ISO 100, 1/200s. Top: 24mm, f/5 Left: 90mm, f/2.8.