It depends on how it was designed of course. One always hopes a shift lens is designed with architecture in mind, meaning it would be well corrected for distortion, but it depends on the lens. Take the Nikkor PC-E lenses for example. The 85mm and 45mm are virtually distortionless as expected (particularly in the 85mm focal length). The 24mm has visible barrel distortion near the edges. The Canon 24mm TSE-II on the other hand has virtually zero distortion.
True also for Canon's TS-E 24 f3.5L first geneation PC lens. These lenses are designed from scratch to be free of distortion; they have to be: why build a PC lens for architecture if it is going to have distortion as a visible fault?
.::Gary Rowan Higgins
One beautiful image is worth
a thousand hours of therapy.
"It is horrifying that we have to fight our own government
to save the environment."