NEW YORK, N.Y. (AP).- People look at some news photos shot on Sept. 11, 2001, and wonder how those who took them could bear to keep working in the face of such tragedy. Richard Drew said his lens acts as a filter: “The things are happening over there, on the other side.” Another Associated Press photographer, the late Marty Lederhandler, put it this way: “I let the camera absorb all the disaster or the sadness of an event. It protects ME from the event.” For AP photographers working on Sept. 11, none knew the big picture of what was going on. All knew only what was happening right before their eyes, that it was part of something huge, and that it was their job to record it. Five whose images of that day became iconic discussed how the photos came about, how endless hours