What lens are your using? I would try one or a number of the following: Stop it down a little to gain a little bit more DOF Try to focus on something a little larger that you know is close to the same distance Check with DOF prevue. Try this with manual focus. Or while on manual focus check the distance markings on the lens and set to just short of infinity. Check again, small objects at intermediate distances can be a little tricky with a shallow DOF.