Gorzek wrote:
Your noticeable distortion sounds like the design of the lens. It is not problem, but a fact of the difference between a rectilinear and curvilinear wide angle lens design. Look it up on "Wikipedia". Overlook the normal "BS" from many "Hogs". All the Best, Don Gorzek, Professional Photographer since 1964.
How can noticeably distorted head shapes be "not a problem" I am sure anyone I photographed and offered them a distorted head shape would be upset and consider it a major problem, I am also pretty certain this noticeable distortion is not standard on this lens I know several professional photographers using it with no problem or distortion of a noticeable amount