Originally posted by K2 to K50 Couldn't quite seem to nail the focus on this guy
When I got my Pentax-F 100mm Macro I had to get used to how razor-thin the DOF was at close focusing distances unless I stopped the lens way down. What was your aperture setting? My lens (and undoubtedly yours) is so sharp that people say you can shoot at f/16 and even f/22 with very little diffraction softening. According to
A Flexible Depth of Field Calculator, for a 1.5CF aps-c camera with 100mm lens focused at 1 foot, the DOF at f/8 is 0.08 inches. At f/16 it's 0.16 inches. You get 0.24 inches at f/22. Back away to 2 feet and the DOF numbers go up to 0.39 inches at f/8 and 0.83 inches at f/16.
For macro shots on a tripod I'll often use manual focus.