After talking with Craigus we started discussing his issues he is having with his17-85mm IS .
After reading his responses I suggested he look up any known issues with that ...
I don't know if users have a site like the users have in Nikonians, where issues can be discussed sometimes ad nauseum.
So I suggested he check out a site called KenRockwell This is a guy who is an amateur photographer with an Engineering background. He has been shooting since he was a kid, so I would think he has a few ideas about photography.
At this time Craigus and I have come to the conclusion that his soft focus pictures are due to Diffraction.
I might suggest that if you give him a good read you may come away with some good ideas.