I'll grant you my own 'testing' was anything but scientific. It basically consisted of taking a picture of a textured brick wall about 3-4 feet away, outdoors in the sun. I took several shots at 2.0 and several more at 4.0. Shutter speed was obviously not a factor. The 2.0 shots were consistently softer than 4.0 (which were very sharp.) The dropoff is more than I would have anticipated (enlarging the image was not required to see the difference,) but then again, I've never conducted a test like this. I was only motivated to try it given all the stuff I've read online. Maybe I should try it again with another lens and see if the same thing happens. At any rate, I'm satisfied it's not really going to amount to much if any of an issue with the type of shooting I do - and for what it's worth, that seems to be the prevailing attitude even among those that felt the lens was soft wide open.