In past I started with the 35L, later I bought the 35 Art.
Long time before I had the 24-70 2.8L MKI, I remember that it was known as not sharp wide open, but maybe there is a copy variation.
I decided to try this lens again as I forgot how good (or bad) it was, some recomposed pics at f2.8 seem to misfocus (don't know if it's my user error of shooting in a hurry).
Some pics at f2.8 are sharp in the centre, others not (all with fast enough shutterspeeds), so it's possible to take sharp pics at f2.8.
But it's a bit like darts, and less keepers than with the Sigma, so less reliable...
I start allready getting nostalgia to my Sigma 35 Art and I have the zoom only 1 week
As 24-70 2.8L I is still fastly sold, I will retest it again for a few weeks, maybe I go back to the 35 Art,
despite I have a 50 Art allready, those primes are wonderfull lenses, colour, sharpness, bokeh,... just everything...
Anyone also switched to the zoom but returned to the 35 Art cause he was used to reliable sharp quality ?