Live View blurry on 5D3
 

So I bought a Canon EF 16-35mm f/2.8 L USM II on ebay and used it for the first time today.

Using live view to preview my shots, I got very strange, blurry previews which do not occur on my other lenses.

When I was at 16mm it was fine. At 24mm it was fine. But when I zoomed almost to 35mm, the live view preview is super blurry. I'm not out of focus; in fact taking the photo and then examining it reveals that the captured image is very sharp. But the live view preview is useless and shows the image as totally blurry.

Interestingly, this only affects live view in photo mode. When I switch from photo to video mode, the preview instantly sharpens up to represent what the camera is actually recording. That's what happens in the attached video, which I shot with my phone. The blurry preview is DEFINITELY IN FOCUS on photo mode. You hear the click of me switching to video mode and the live view preview instantly corrects. Despite no change in settings.

Do you reckon you can figure out what the heck is going on?

I'd love to know if it's a lens problem or just a simple setting I need to alter somewhere.

Thanks,
-- John