Let me answer your question indirectly -- focal length and coverage are
wholly unrelated lens characteristics.
Focal length determines image size. A 100mm lens produces the same image
size (magnification) at the film plane, regardless of the film format.
Coverage is determined by the lens's optical construction. A 100mm lens for
a 4x5 view camera necessarily must cover a larger field than a 100mm lens
for a 35mm camera.
Shift lenses for 35mm cameras have much wider coverage than 35mm lenses of
the same focal length. This allows the lens to be shifted without vignetting
the image. The extra coverage requires a much larger front element, not
unlike the front elements of fisheye lenses. However, shift lenses are
rectilinear. Indeed, highly rectilinear -- they have to have low distortion
if they're to be useful.
Shift lenses have been produced in 35mm, 28mm, and 24mm. You're "lucky" if
you have enough money -- Olympus is the only company that ever made a 24mm
shift lens.
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