Canon TS-E lenses are most certainly not "limited to tilt in just one direction".
Peter,
I expressed that badly, didn't I. Of course I meant in one direction (or along one axis) in relation to the direction of the shift. For example, if I wanted to use shift for perspective control of a tall building and at the same time use a bit of tilt to get the flower bed in the foreground tack sharp, I wouldn't be able to do it the way my lenses are set up. If I took the lenses back to Canon to get them to orient the two movements along the same axis, then in a similar situation, but instead of flower beds in the foreground, say an interesting structure close-by on my left, I would not be able to get that structure on the left tack sharp through use of tilt.
It's a limiting factor, but not all that serious perhaps.
That's true every time you increase format size. Medium format is easier to focus than 35mm, 4x5 is easier to focus than medium, 8x10 is easier to focus than 4x5.
What should also be mentioned is that every time you increase format there is a DoF penalty (in relation to the same f stop, in case you misunderstand me) which creates a greater need for tilt movements. For example, I find with my 5D, in situations where I want maximum DoF, I can use f16 with very minimal loss of over all sharpness. The increased DoF outweighs any marginal resolution loss. To get the same DoF with 8x10 format (in relation to picture height) I would need to use f128. By doing so, I would be compromising resolution so greatly, it is doubtful such a shot would offer any resolution advantage over a 5D image at f16.
My point in general is, not only is it more difficult to get the benefits of tilt with 35mm TS-E lenses, as a result of focussing difficulties and other limitations, but the need for the 'apparent' increase in DoF with the smaller format is less. The benefits are less and the trouble is greater.
Okay! Someone prove me wrong and post some dazzling macro shots that have benefited greatly from tilt with the TS-E 90mm .