If this happens in, for example a Canon 5D, with adapter, it most likely means that the focusing screen is not "justiert", not placed at the right hight. Canon apperently presumes, that people with a AF camera do not need a properly placed focusing screen. Canon sellls a set of 10 "shims" to do this yourself. If this happens in a Contax body you may want to check if the mirror has not slipped downward from its metal frame. Apperently after some 20 odd years, the glue that hold the mirror in place losens up and the mirror can slip down. I think this is a known problem in the RTS and RTS@ and maybe other bodies. In a proper SLR what you see on the focusing screen, is what you get on the filmplane, even if the lens does not focus on infinity.
If you need more info on the Canon shimming, give me a call, i did this procedure on my 5D..

Jaap Jan

P.S. I think the focusdepth in the 28mm lenses is not shallow enough to show up the problem.