I became one of Time's two photographers covering President Reagan in his second term. But this kind of work really began for me during the Bush administration [1989-1993]. Taking "private" photos at the White House means you can only go so far. During the Clinton administration, I was granted a lot of access. I walk into the room and look to see who is there, the light, the action, the mood. I see tension, or I hear laughter. I don't want to interrupt the action, the president, in any way. It's absurd to think that I was just a fly on the wall. He knows you're there.

I never speak to the president. He might say, "Good morning, Diana," and I say, "Good morning, Mr. President," but that was it. I wanted him to ignore me. If they looked at me like they might talk, I would look down, put film in my camera. I wanted to see him talk to other people -- not me. I wanted to shed light on the true character of the president at a given moment -- is he angry, happy, roaring with laughter, mean as hell? I never said, "Oh just a minute, just one more shot." Never. You don't overstay your welcome with the president.

I've sat up at night worrying, did the photo come out? So many things have gone wrong. No film in the camera, the wrong film; it's underexposed, overexposed. So, you go with your gut and just shoot it. Like once, it was the evening before the impeachment proceedings at the White House, and President Clinton turned and put his arms around Hillary's neck. It was such a quick gesture. I squeezed the shutter and thought, "Oh, if that had only been in focus, if only the light was right -- I had the moment." I didn't sleep that night. The next day, the call comes from my editor: "Hey, guess what? You got it. Terrific." Other times, it's been, "You blew that one." I can only show you what I saw in the hope of imparting it to you. He is a man, not a president, a woman, not a first lady. That's what I'm watching for, to show something about their humanness. Whatever I see, they have let me in.

-- Interview by Patricia Dempsey