Anybody with Internet access and an interest in John Kerry has probably seen my photograph by now -- or the part of it that I made, anyway. The other part is a fake, a visual lie. There's an AP credit down in the right corner. That's a lie, too. As far as I know, John Kerry never shared a demonstration podium with Jane Fonda, and the fact that a widely circulated photo showed him doing so -- until it was exposed in recent weeks as a hoax -- tells us more about the troublesome combination of Photoshop and the Internet than it does about the prospective Democratic candidate for president.

There have been two Kerry-Fonda pictures circulating around the Net, both promoted by conservative groups eager to link Kerry to Fonda's support for North Vietnam during the Vietnam War. One of these photos is real: the picture that shows the two of them in the same audience, some rows apart, at an anti-war rally. But the other, in which an angry-looking Fonda appears to be in mid-speech, with Kerry at her shoulder, is a paste-up job that started with a photo I made in 1971, when I was a 20-year-old student with big ideas about the power of photography.

I was trying to document the entire era with a camera. I believed photographs could bear witness, could help Americans understand each other, and I had spent the previous two years making images of a divided nation: antiwar rallies, veterans' parades, students facing off against national guardsmen. One afternoon in June, I attended a large rally in Mineola, N.Y., close to my parents' home. I recall the day vividly: the guy with a hardhat, the girl in a peasant blouse, the thousands of people sitting on the ground with American flags and peace signs. Speaker after speaker came to the stage to denounce the war in Vietnam. I kept shooting.

THE REAL DEAL: JOHN KERRY, JUNE 13, 1970, MINEOLA, NY Photo by KEN LIGHT/Corbis

Finally, one speaker in particular caught my attention -- a highly decorated Vietnam veteran named John Kerry. It was a powerful experience, hearing a war hero speak so forcefully against the war, and I made a few more photographs. I was still very young, but I'd learned enough to know that negatives are sacred, and that every roll of film must be carefully filed away for future use. So Roll 68 went into my file cabinet, where it remained until just a few weeks ago.

Watching Kerry emerge as the Democratic front-runner this year, I recalled that I had an image or two of him from way back when. The negatives were easy to find. Captioned and scanned, they flew off to the New York agency now representing some of my work. I have remained a photojournalist, and now teach students who are only a little older than I was in 1971, but who are working in a different world. Who could have predicted that my Ethical Problems in Photography presentation would be showing young journalists how National Geographic moved one of the Egyptian pyramids to make it fit on a cover better, or the way colleges seeking a more diverse image edit African American faces into sports crowds that look too white?

FAKED PHOTO WITH FALSE CAPTION

It's not that photographic imagery was ever unquestionable in its veracity; as long as pictures have been made from photographic film, people have known how to alter images by cropping. But what I've been trying to teach my students about how easy and professional-looking these distortions of truth have become in the age of Photoshop -- and how harmful the results can be -- had never hit me so personally as the day I found out somebody had pulled my Kerry picture off my agency's Web site, stuck Fonda at his side, and then used the massive, unedited reach of the Internet to distribute it all over the world.

I've spent a lot of time answering questions about this in the past couple of weeks, and this time, as far as I can tell, the Internet has come as close as it gets to a correction. If you use a search engine to look for my Kerry picture now, you'll find the hoax explanations before you see the photo itself. So what do I do now about the conspiratorial Web site that's trying to convince its readers that my original picture was the hoax -- that Fonda really was at that podium with Kerry, and somebody edited "Hanoi Jane" out? All I can do is pull Roll 68 out of the file cabinet again. It's my visual record, my unretouched truth.