There are threads re the ribbon cable which I have already had replaced on this lens after not focusing at all about a year ago but now I have noticed that if I set up a test rig to check the sharpness, camera set on manual, 200 iso, F8, tripod then when I focus the first time it gets it smack on then subsequent focus is out. I'm checking the focus by using a test print with focus text and lines on it and connecting up to the computer then using live view and magnifying. It's only a fraction out but noticeable. I can correct it on the computer screen by clicking the focus arrows a couple of times and then it's fine, however and here's the mystery if I then move the focus ring to out of focus and then refocus automatically it gets it smack on again. Try again and it's out and so on. Camera triggered remotely either by computer or remote so no chance of wobble.
Now in all honesty I have only just started checking my lenses and this is the first I have noticed it being slightly out and may well have been out for some time and possibly after repair (way past my 3 months warranty though). Both my other lenses (Prime 50mm f1.8 and EFS 55-250 are spot on every time)
Anybody noticed anything similar. S'pose it's another trip to the repair centre but interested if anyone else has come across this and if not whether anyone will check there lens. You may not notice the sharpness on day to day photos but it's there and it's not right.
Finally a caution if you get your lens fixed check it thoroughly for sharpness before any warranty expires just in case.
