Originally posted by Edgar_in_Indy I figured it had something to do with the overhang of the lens body itself
It does. In recent DSLR's Pentax has been visibly and clearly reducing the body clearance above the mount. It's easily visible from model to model. The latest reduction in clear space above the mount is also poor design on behalf of the K-1 body designers, IMHO. It's seems just practical to keep the area around the mount reasonably flat and clear, like previous and older Pentaxes did (and other brand DSLR's do), not have the body arch up immediately from the lip of the mount plate.
So I think Sigma and Pentax share responsibility for this problem. Both contributed to it.
It could have easily NOT been a problem if Sigma and Pentax had talked to each other during the evolution of the K-1, as partners in the Pentax eco-system. Or if Ricoh had simply run a broad beta test program during the evolution of the K-1, so that the K-1 body design would have been exposed to the Sigma lenses that real-world users would likely mount on the K-1, allowing the K-1 designers to nip any physical design problems in the bud.
My Sigma lenses have no problem with the K-1, even though they are on the 'problem lens' list, so I don't have a personal axe to grind here with either Sigma or Pentax. Just observing this fracas with a little disappointment that experienced Japanese designers and engineers in both camps could make such simple but annoying blunders. I hope Ricoh or Sigma don't ever work together on aircraft design.