For a while now I have not been happy with focus autofocus on my D7000 camera so I ran an experiment
I printed out two test patterns, laminated them so they would remain flat and then taped them to a glass
frame on the wall which was sitting flat. I measured 4 meteres from the wall sat the tripod on a solid table
inside and set up the remote trigger. I was watching the camera focal point and it picked the same focus point
iso was set to 100 and set to aperture priority.

at 4 metres at f/1.4 0.8 sec

test-1 by starmedal, on Flickr

at 4m f/2.0

test-2 by starmedal, on Flickr

at 4m f/4.0

test-3 by starmedal, on Flickr

at 4m f/8.0

test-4 by starmedal, on Flickr

at 4m f/11

test-5 by starmedal, on Flickr

at 4m f/16

test-6 by starmedal, on Flickr

Why is the focus so out of whack at f/1.4 and f/2.0 it is not until f/8 that I believe the focus is sharp enough do I have a dud camera or is there
some thing wrong in my technique.