Though he was there to see the bears, Bruce Danz wasn’t expecting such an up close and personal greeting from one, much less its playful farewell.

The rare interaction was captured on video by Mr. Danz, a retired doctor who is a photographer.

He was with a group of photographers this month when the cub briefly broke away from its two siblings and mother bear in Katmai National Park and Preserve in southern Alaska.

The tour guide, Jerry Jacques, said he hadn’t seen this happen in the nearly 50 years he has been taking visitors around southern Alaska.

For Mr. Danz, though, it was only his second trip to the state, and the chance meeting happened on the sixth day of a visit that he had booked so he could photograph coastal brown bears during their salmon run.

He was set up in the preserve area, outside the national park, Mr. Danz said, and had become accustomed to seeing bears walk close to people.

“We try to maintain at least 50 yards from bears and set up to photograph them, allowing the bears to do what they want to do as far as they can,” he said on Sunday in an interview from his home in Wisconsin. “But sometimes the bears walk really close to us, and we don’t have time to get out of the way.”

That’s precisely what happened.

“They rounded a bend and — bang — there they are,” he said. “The mom went out into the stream to go fishing, and the little bears just sort of trotted along in front of us.”

The photographers stayed still, and one of the six-month-old cubs — instead of following the leader — diverted from the family’s path to sniff out Mr. Danz’s boot.

“He momentarily glanced upward toward me, right before he took a nibble, as if to say, ‘Uh, is this OK?’” Mr. Danz said. “He took a little nibble, and all I had to do was move my foot an inch, and that was enough to get him to let go and get back in line.”

Just before and during the contact, Mr. Danz and others gently encouraged the bear not to get too close.

“No, bear. No, bear. No, bear. No, foot. Easy. That’s my foot. Go, bear,” they said in the 30-second video that Mr. Danz recorded.

“I didn’t feel anything other than a little tug,” he said. “I was surprised, but really not frightened. My only concern was not to let mama get concerned about it. And she didn’t seem to care. She just kept trudging on.”

Then it was time for a farewell.

“As he scampered away, he looked back at me, like a side eye, sort of like, ‘You said this was OK.’”