Rocker,
It looks to me like certain areas of your pics are sharp, and then they fall off to softness. This is a pretty classic example of the need to tweak your settings to get more DOF.
Even though you are not going extreme in your aperture settings, you still are in the range where you need to pay attention. I've seen real subject isolation at f/8 -- it all depends on managing the variables of aperture, focal lenth, distance from subject and distance between subject and background.
It looks like you were very close to your subject, which presents a very sensitive DOF situation. But, with the last pic, you seem to have struck a good balance, right?
The whole time I was about 4 feet from my subject and she was about 5 feet from the background...might of that been the problem? Also is there a difference in the plane of focus if Im standing and shooting her or if Im a bit crouched?
Please try some shots of static objects from a tripod of other stable platform and get back to us. These images have no EXIF data and without being there we can't know what was happening when you shot these frames. We will also need 100% crops to distinguish between OOF and motion blur.
Unfortunately I do not own a tripod anymore. I wonder why these images have no exif data? I can add shutter speed to each image but I trust you not one is lower than 1/160th and the max is 1/320...
and if Im not mistaken, these are 100% crops?
