I also have this lens, and it is also a just slightly loose on the front barrel. I should take it apart one day and try to tighten it. I have not noticed any image degradation when using this lens though. This type of image did occur once on my Canon Demi S when I first got it, the lens was not tightly screwed down onto the body, It is supposed to be screwed in with 4 screws, and when I opened it up, only one was on, the two others were very loose. This allowed the lens to tilt a bit if pushed.