eddieking

Help. I am having trouble in getting sharp pictures with my k10. I know it's not the camera- it's me. I took some pictures of a street sign at f3.f4.5, 6.7, f9.5, f13. ALL was done at 18mm. The distance from lens to sign was 23in. And this was done on a tri pod with anti shake off. When I zoom in on all of the pictures on the compute to see if they came out clear, all are fuzzy but f9 and f13 are sharp. I am new to digital camera. Shouldn't all of the shots be clear since we are only talking about a distance of 28 inches. Help me understand what I am doing wrong please