I have been trying to make some shoots with a friend recently with my d90 (35mm f/1.8G) and I noticed that I have much sharper images when using the manual focus instead of the autofocus.
My friend is always slightly blurred when using the autofocus (even with the single point focus). It's not so much visible if you look at the image globally, but if you start zooming, you can see details (like beard) is blurry.
The problem is that manual focus is very sensitive, and then takes time to be perfect, but sometimes I need to be fast, or if I or he moves, then I have to restart all over again.
As mentionned, I tried with single point autofocus, but even putting my subject at the center while focus, the focus is made on the background, as you can see on the images. On the uploaded images, in the AF, I put the leaves (my subject) at the center, and I focused on it, but it failed. I tried with bigger subject (like a person) and it still fails most of the time to focus properly. Am I using the single point focus badly?
What could I do to have a very accurate autofocus?