Ronald Reagan first caught my attention in 1964 when I was at Queen's University in Kingston, Ontario (Canada). I was there for two years studying math and physics, and I can remember only two things from my stay. Heisenberg's Uncertainty Principle has remained with me ever since; it states that the very act of observing a phenomenon changes the nature of that phenomenon. I've always considered that peculiarly relevant to journalism.

I can also vividly recall watching a televised fund-raising speech Ronald Reagan gave for Barry Goldwater. Looking back on it now, the speech launched Ronald Reagan's political career; because of it a group of wealthy Californians encouraged Reagan to run for governor. But in 1964 he was not exactly mainstream. It was not particularly fashionable to defend Senator Goldwater, nor, I suppose, was it very fashionable for a Canadian university student to be interested in someone who did. But there was something about Reagan that struck me as remarkable, even then.

Eleven years later, long after I had become a professional photographer, I jumped at the chance when Time magazine asked me to cover him. My editor at Time was less enthusiastic about the project than I was. Reagan was still regarded as something of a right-wing kook and no one thought he posed a very credible threat to Gerald Ford. But I had a hunch. I still carried the memory of the Goldwater speech. I actually wanted to spend more time on the story than the magazine wanted me to. Eventually I persuaded them. I think I got paid for only two days of a four-day trip, but I got what I wanted. In fact, most of my favorite photographs of Reagan came from those first intimate days with him on his ranch near Santa Barbara.

When I was winding up my trip, my editor called, a little frantic. He said, "We've just scheduled Reagan for a cover. Can you stay with him?"

And the rest is history.

When Reagan defeated Jimmy Carter in 1980, the photographer who had been hounding the "right-wing kook" for four or five years found himself in a rather enviable position. The White House decided they wanted a personal photographer for the president, someone to provide a pictorial documentary of the Reagan years. They looked around and I was pretty much it.

It was truly an honor to be the personal photographer to the president, but it was the documentary aspects which interested me most about the job. Before I got hired, it had always been terribly difficult covering Reagan at big public events. There were so many other people fighting to get the "shot" that your abilities as a photographer weren't nearly so important as your ability to bull through a crowd. Working on the inside, I had no restrictions whatsoever. I didn't really have to worry about logistics, because most of the logistics were worked out in advance. I could concentrate on taking pictures.

Many of the scenes I witnessed and occasions I covered during my more than four years at the White House will always remain with me. It really was an opportunity of a lifetime. But one day in particular - not a happy day - stands out in my memory. I'll spare you the details of his attempted assassination, because I'm sure you've all read about it a million times. But I clearly remember when I arrived at the hospital and saw the president wheeled by on a gurney. I froze. I knew I had come to respect Ronald Reagan, but I didn't realize how deeply my affection ran until that moment in the hospital. It came as a complete shock. I felt as if my own father had been shot. I just sat there for an hour, devastated. It never occurred to me to take any pictures.

The rest of my years there were a blur of handshakes, special moments and historical events that I feel privileged to have documented.