@TheRoff...


Please have a look at the following url, it seems that there are others out there with thesame issue. Some have submitted the lens to Canon for further analysis while others cranked up the ISO and stepped down a few to correct.


http://photo.net/canon-eos-digital-camera-forum/00Djmn


I've got the same lens, however mounted on a APS-C body.


Sorry, not sure what else I can say...[:$]