It ain't easy:

The science and engineering team built a whopping 490 commands to accomplish the most complex robotic arm operations on Mars yet. Opportunity took three mosaics on the area dubbed "Last Chance," using the microscopic imager, creating 128 images in over 200 arm moves. Each "frame" of these mosaics required multiple microscopic images. There are two reasons for this. First, the microscopic imager does not have auto-focus, so the team needed to have Opportunity take and return multiple images at each location at different distances from the rock to get at least one in focus. A second reason is that the team needed Opportunity to take an extra image at a slightly different angle for each frame to create the right conditions to build stereo and computer-generated graphics of the "topography" of the rock area up close.