Focusing after back swing

[xkaes]

The rear swing, tilt, shift, alter perspective.

Rear swing and tilt alter the perspective, but shift & rise/fall do not. That just moves the film to a different part of the IC -- or vice-versa.

The Depth-of-Focus at the film plane is very narrow -- unlike the Depth-of-Field at the subject. Swinging or tilting the rear standard will quickly move the edges of the film out of the narrow Depth-of-Focus. This is very apparent on the ground glass. To get it back in focus -- if that's what you want -- the front standard is moved back toward parallel with the rear standard.

Re-focusing and stopping down will help, just as it does when tilting or swinging the front standard alone. The difference is that tilting or swinging the front standard does not alter the perspective -- just where the Depth-of-Field lies.