I looked at the pictures again and I have bad news for you. My body thinks it's the same thing. APO Sigma should give you much better results then this. The only way to be sure you have to test your lens with the same or hight version of Canon's body, XTi or 40D would do for sure. Their is a chance that an other 350D would have the same issue. May be they all after certain amount of shots must be calibrated I wouldn't take a risk.