Canon's CPS (Canon Professional Service) can cost a bit. They recommend getting the lens and body calibrated together. This article contains a lot of info on testing... http://www.canonrumo...to-test-a-lens/ I've also attached a test chart. Don't get too hung up on testing though. Some people take it far too seriously and examining images at large magnifications has nothing to do with real world scenarios. I've never felt the need to send my camera or any of my lenses in for adjustment. All of my lenses fall into line with what I've read in reviews. My 100-400mm for example isn't that sharp wide open,but stop it down to f/8 and it's razor sharp. I always use http://www.the-digital-picture.com/ to research a lens and look at the test charts on there. You can also directly compare lenses on that site. Quality of the lens will have a lot to do with how sharp a lens is too. We can't expect a $200 lens to be as sharp as a $2000 lens. ISO_12233-reschart.pdf