People have been arguing the ethics of picture-taking ever since the camera was invented.

The Plains Indians were wary of the big box cameras that followed the homesteaders out West in the 1800s. Or so I have read. The Indians believed that photographs were more than just two-dimensional likenesses of themselves; they thought the camera had the magical power to steal a person’s spirit and trap it forever on a plate of glass.

Photojournalists debate the ethics of pictures every working day. Just when is it permissable to aim a camera at an unsuspecting subject and publish the results? When does the significance of a news story allow us to throw the rules of courtesy and privacy out the window?

As the early Indians might have asked, just when is it acceptable to run off with a piece of a person’s spirit?

We’re more sophisticated than the Indians of the past, of course. As dwellers in a high-tech world, we understand that a photograph is nothing more than an image created by the manipulation of light. No magic involved, no demons lurking inside Nikons, waiting to wrench the souls from the innocent.

The other day, though, I experienced a little of what the Indians must have felt when they first peered into that cold, all-seeing glass eye. The spirit-stealer in this case was a camcorder, one of those video cameras that some people use to forsake the joy of the present moment in order to record it for future viewing.

We were at Sand Beach, in Acadia National Park, on a day filled with mist and fog. Only a few small groups of people — families, lovers, friends — sat on the sand or strolled along the water’s edge, talking quietly and looking out over a wind-whipped sea that was capped with foam.

My kids and their three little cousins, five in all, played in the sand a few feet from us. They dug holes frantically and squealed as the waves came to fill them up.

We adults — parents, uncles and aunts — were talking above the mild roar of the ocean when a man and a woman appeared in our midst. They looked to be in their early 40s. She carried a 35-mm camera with a motor drive attached, and he had a camcorder resting on his shoulder. Intent on their photography, they did not speak.

Suddenly, like a soldier under attack, the woman dropped to the sand a few feet in front of us to photograph a few resting seagulls. Her motor drive whined and clicked. The gulls shrieked and ran. The woman scuttled after them crab-like through the sand, her eye pressed to the viewfinder, firing away as the birds took flight.

It was an amazing display of photographic intensity.

The man, who had been filming the same birds with his camcorder, spotted our children and hurried over to where they played. And this is when it happened: He began filming our children — up close and personal, as they say on TV. He filmed them from a standing position and he filmed them on his knees. He poked the camera into the middle of their little group and filmed them from the ground up.

Then he began circling the children with his eye glued to the viewfinder. He recorded every move and sound they made, as if the kids were merely a part of the scene, like the rocks, the birds, or the sea. The children looked up at the man, then at us, then back to the man. Finally, the camcorder maniac left and walked silently down the beach with his companion, gobbling up the vista with his machine.

Here’s the rub. Never once had he uttered as much as a single “hello” to the children or to us, their obvious guardians. As I thought about it later, I came up with a list of possible explanations for his strange behavior: The man was a filmmaker, studying the dynamics of movement. Or he was a psychologist, observing the unrestrained behavior of children for a scientific paper. Or he was a talent scout, hunting for kid actors. Or he was a pervert, plain and simple.

I ruled out those theories and concluded that the guy was just a camcorder nut, one of a new breed of people whose mission is to comb the planet and record every moment of human history on tape. My kids just happened to get in the way.

One thing bothers me, though, and this is where the old Indian beliefs come in to play. Somewhere at this moment, in a living room in California or New York or Maine, a strange man may be watching movies of my children playing on a beach. If cameras can really steal the spirits of people, then this guy made off with a few that are close to me. Is it really any different from finding snaphsots of my kids in a stranger’s photo album?

Perhaps the Indians had a point after all.