I am looking at buying a second hand Canon 18-135 f3.5 lens. I only want it for a walk about lens with my 500D. However, I am wary of counterfeit lenses and so forth, so I don’t want to look at it, test it and have it work okay for it to pack up in a week after paying money for it. Will I be able to tell if it is genuine from the images? I know the exif data may be dodgy with a fake one, but bringing a laptop to check this would look very distrusting. Any advice appreciated.