Golden copy of 50mm 1.8 II sample picture
Test shots are with APS-C 18mp sensor since its actually more demanding on optics in the center with smaller pixel pitch, etc compared to my 5DMKII (and I'm having fun shooting a Rebel again).
center 100% crop
This is the only copy I've found that gives me confident AF 99% of the time. I took this handheld and I only took 1 shot...no more have to take 5 shots and weed out out of focus ones anymore...this one just works . Uploaded it to my computer and was pleasantly surprised by the sharpness, but on the otherhand it also makes more sense. If you want a nifty fifty to have good AF...IMO it has to have decent sharpness completely wide-open. Many people have lowered their expectations and believe the 50mm 1.8 is going to be terribly soft wide-open...true it gets sharper...but if it really is terribly soft IMO it will strongly correlate to much poorer AF performance!
Mine focuses fast and confidently and I am already loving it!
center 100% crop
Here is another set...brick wall + foliage. You can see its a bit soft lower-left side...and again handheld so not even sure I have the plane of focus right...but again with the crop you can see the center sharpness is pretty damn good. I don't expect perfection at wide-open and for this price, but I think the center/midrange sharpness is good enough for it to cover all AF points confidently on either my APS-C or 5DMKII (which only has an APS-C sized PDAF sensor array anyhow).
Going to go see how it sharpens up at f2.8 now...but IMO if you want a nifty fifty with good AF...it has to be decently sharp wide-open too.
edit - just took some f2.8 and the corner sharpness is annihilated so I'm very happy with this copy...I also think my plane of focus was slightly off in these examples to exaggerate the border softness (pretty difficult remember as I'm handheld shooting f1.8). Also if I'm shooting f1.8 border sharpness is rarely an issue anyhow...can't wait to try it on my 5DMKII later.