Errol Morris's documentary about Abu Ghraib is startling, not because of the now infamous images (though they have not lost their capacity to startle), but because Morris is sincerely interested in the people who took them. Framed by Sabrina Harman's increasingly uneasy letters home to her lesbian partner, Standard Operating Procedure seeks answers to questions that are usually purely rhetorical: Who would do such a thing to another human being? And why would you want to photograph it? (See movie times..) ANNIE WAGNER