Hi, there is two topic about this, writing here too.
I have Sigma 17-70mm F/2.8-4 C there was a focus problem at wide angles. I tried with different lenses. Tamron 17-50mm F/2.8 ( i can't call it test, just a few photos ) no mistake. Canon 70-200mm F/2.8 II ( a lot of photos with different...