Originally posted by Wayneheim
The problem is that to get it to focus at all I have to move the bellows all the way into the body of the SG
It looks like you have discovered the problem with LF/dSLR adapters. The sensor on your Pentax is 45.46mm behind the mount flange. As a result, the taking lens must be moved that much closer to the rear standard to attain infinity focus. With most LF cameras this means loss of most movements, if indeed the camera is able to collapse that far without "kissing" the lens rear element to the dSLR body
There are systems using the dSLR body as the rear standard in conjunction with a bag bellows that work with some success though the shortest usable lens is still likely to be in the 90mm or greater range.
Steve