Brand new lens picked up just yesterday. Testing on 6Dii body. The image is blurry when subject is about 10-15 feet away at f/2 and f/2.8, improves a bit when lens is closed down beyond that. I've confirmed AF point with DPP software, but lens doesn't appear to be front or back focusing as NOTHING is in focus, the entire image is blurred, more like when camera shake is the issue. Except I also eliminated camera shake, as this is an IS lens and anyways I also tried at higher shutter speeds and the problem remains. I also tried it with IS off, same problem.
Lens is fine when subject is say pretty close or far away. It's that midrange that presents a problem. To add a further wrinkle, when I use Live View, the image is fine. It's just when I use the OVF that this problem shows up. Kind of befuddled as to what could be the issue here.
I don't presently have another Canon body to try this on, but I do think the problem is with the lens as other lenses on this body don't exhibit the same issue.
I am probably just going to return the lens for another one, but I do want to make sure I am not missing something obvious or I should try something else.