This lens is very soft at all focal lengths and I found its sharp spots between 5.6 and 9.0, outside of that above 9.0 it got incredibly soft even in the center of the image.  I might've had a bad lens, but I know multiple people who owned this lens that sold it quickly shortly after purchase.
When shooting at a resolution higher than 1080 the softness shines through no matter what focal length or where the iris is set at.
I got rid of this lens very quickly, while it looked good compressed to 1080/720, it showed glaring weaknesses compared to other lenses on the market.
I loved it on my 7D, I can't stress how disappointed I was with it on my Scarlet and other cameras I operated using this lens.  I found the Sigma 17-50 to be much sharper.  Other issues I had with the 24-70 was purple fringing, soft in the center at times, very short focus throw, and it often fell victim to gravity when shooting at a downward angle.
I also felt it was semi poorly built as I went through 2 and both focus rings broke while pulling focus during concerts.
I might've gotten some bad eggs, but I was highly let down with this lens.