Please forgive me for not having time to read through all these pages- I was wondering if this lens has any vignetting wide open? I shoot a lot of newborns and my Canon 24-70 mkII vignettes a lot wide open- which can be nice sometimes, but I am fixing a lot in post because I don't always want a vignette with a newborn. I have looked over my images and many of them I shoot around 50mm. I have a Zeiss 50mm, but for older babies that move a lot, I prefer to have AF. So I was thinking of getting this lens, but want to make sure I would not have the same issue with vignetting. I might not be shooting at 1.4, maybe 2.0 or 2.8. TIA!