One thing I learned recently is that each lens has specific sharpness characteristics at different F-stop settings. I did an experiment in my basement with my Tamron 90mm F 2.8 Macro lens.
I took the same picture using a tripod, ten second delay and manual focus. The only thing I changed was my F stop settings. At F 2.8 the first picture was fairly sharp, but had little Depth of Field. (DOF) Picture #2 lost some sharpness, but increased the DOF. Finally picture #3 lost even more sharpness at the center point, but had the greatest DOF.
The lesson I learned was – where do I want the greatest clarity? Do you want it on a specific point or a larger area – then choose your F stop wisely.