ha... i wondered how long it would take for ken rockwell to be mentioned on here...
the soft focus is mostly down to the fact the the depth of field is so narrow large portions of the image are likely to be out of focus ... it takes a bit of getting used to ...
in the case of the image above im sure it sould have been made sharper with the 1.2 lens and perhaps sharper still with the 1.4d or 1.4 afs that you have... but i rather like the soft focus effect in this instance