I'm starting to stretch the legs my 105mm Micro, but I'm not getting the DOF I want. For instance, the shot below I had to push in on the tiny shell to fill the frame and get rid of a bright distracting background. In doing this I was right at the minimal focal distance. I've tried closing down the aperature to f9 and all the way down to f32 but I cannot see the difference. Part of the shell will be in focus while the rest of it is blurry. Is this due to the fact that I'm at the edge of the focus range or am I missing something else?
This was shot handheld and manual focus. Normally I would have used a tripod, but I didn't have one on this trip. _DSC0831.jpg