Both copies I received from Crutchfield were sharp.
1. I set the camera on tripod and took some pictures with View finder at 24, 35, 50, and 70mm at f2.8 ISO 100. My target was stucco wall
2. Same setting, under LiveView, took some pictures at 24, 35, 50, and 70mm at f2.8 ISO 100
I didn't see much different btw viewfinder Vs LiveView
3. I ran the lens through FoCal(x50 lenght) and repeated the steps above
Results: FoCal suggested -2 @ 24mm(sharpness around 1100) and +1 at 70mm(sharpness around 1150ish)
Again...I compared pictures before AFMA Vs after AFMA, there is no different in real life shooting. At the end, I set both ends(W+T) to zero on my 24-70 in my 5D III.
I didn't know at 24mm this lens has vignetting, so I asked Crutchfield for another copy. 2 weeks later, Crutchfield sent me my replacement. I compared two lenses. Same vignetting. According FoCal, the 2nd copy is a bit sharper. AGAIN...no different btw the two - in term of sharpness in real life shooting.
At the end, I kept the 2nd copy and returned the 1st. Here is my most recent pix I took inside a pre-school class room with no flash at f2.8 (5D III +24-70 II)