The lens finally turns on him: Bill Mills, 72, snaps shots at Beverly Farms Elementary in Potomac. Because his position as the only full-time photographer for the school system is being cut, Mills plans to retire from the job he took on a whim in 1967 — that also introduced him to his wife. (Neil Rubino)

Even with a camera pressed against his nose, you can tell Bill Mills is grinning.

Seventy-two years have left wrinkles around his eyes that deepen when he smiles. His dimples appear from underneath his white beard.

Mills has been at this job for 46 years. He said he still looks forward to going to work every day. He’s not sure what he’ll do now.

Mills, the photographer for Montgomery County public schools, one of the school system’s longest-serving employees, is retiring at the end of the school year.

He leaves behind millions of photographs that have captured the day-to-day of a growing, changing school system. The archive is immense; file folders and boxes of black-and-white contact sheets fill the back of a storage room in the school system’s central office in Rockville.

Mills would be difficult to replace, if the school system was replacing him, said his supervisor, John C. Marshall, the system’s supervisor of editorial graphics and publishing services.

Mills’s position, the only full-time photographer, will be cut. The system will use other staff members and contractors to fill the void, Marshall said. Having Mills has been a great resource, but also a luxury, he said.

“It’s the way of things,” Marshall said. “We will do our best to hold things up.”

From behind his lens, Mills has captured the most obvious shots, such as superintendent profiles and mothers hugging their kindergartners goodbye for the first time. He has also witnessed history, taking photos of teachers on strike in 1967, Rosa Parks at the opening of the Olney school named in her honor, and a few presidents.

He has taken photos as he rappelled with students at Great Falls, crawled through caves on a spelunking field trip, and went whitewater rafting with Bethesda-Chevy Chase high schoolers.

A more mundane, but valued, contribution is the “20/20” photo library that Mills produced each year, Marshall said. The library comprises 20 shots in 20 standard categories such as math in the classroom, staff development and reading. These images were used for many things, such as marketing, printed materials and the school system’s Web site.

“Bill has provided us a living history of the school system of the last 40 years,” Marshall said.

It wasn’t Mills’s intent to make a career out of his job.

After he finished taking courses at American University in 1967 for his master’s degree in studio art and art history, he said, not many companies were hiring full-time photographers.

At 27, he took the MCPS job on a whim, expecting to stay a few years.

Soon he realized that the positive nature of the work fulfilled him.

He began to get to know principals, teachers and students. He said that when he met his future wife, Helen, on the job, the deal was sealed.

Helen, who was working as a media specialist for Brookmont Elementary School at the time, was visiting the central office.

She denied his request for a first date, but, he said, he was determined. When he was assigned to take photos of a school library, he said, he knew exactly what school to visit.

“I picked hers,” he said.

From there, Cupid took over, said Tom Bourdeaux of Goshen, who was one of Mills’s supervisors at the time.

Bill and Helen have been married for 41 years. They live in Chevy Chase.

Photography was different when Mills started. Mills remembers how the chemicals used to process photos in his darkroom used to eat away at his hands.

Editing five to 10 photos by hand would take all day.

Bourdeaux said Mills’s photos were always high quality, and he was always cooperative; Bourdeaux still refers to Mills as “one of his favorite people.”

The school system looked different back then, too.

There were 115,000 children and 9,000 staff members working for 164 schools when Mills started, said schools spokesman Dana Tofig. In 1968, 93.6 percent of students were white, according to school system data.

Around him, Mills witnessed brick buildings multiplying, growing bigger and more grandiose. He saw diverse communities grow. Now, there are 202 schools and 149,000 students, and only about 33 percent of the students are white.

He watched as blackboards changed to white boards, then to digital boards. He saw the trends, such as open classrooms, come and go.

Amid the changes, Mills noticed one constant — the interactions that he captured between students and teachers.

“The teachers always seem to be trying to think of some way to reach the students,” he said.

And no one minded him hanging around, he said.

“Maybe that is why I have worked here so long,” he said. “I have always felt welcomed by people.”

Mills has the 13th longest tenure of any school system employee, Tofig said.“We say, when is Bill going to retire?” Bourdeaux said. “It seems like he would want to get out of there.”

His friends joke about it.

On a recent day at College Gardens Elementary School, a kindergartner with pigtail braids and a purple dress watched Mills as he took pictures in her classroom.

She walked up to him and began to ask questions.

Mills bent over to whisper to her.

“I’m not really supposed to be talking to you right now,” he said, in his singsong voice.

The girl kept talking.

“I find myself thinking about how well Bill does with young people,” Marshall said. “He is like a grandfather.”

When Mills is complimented, he lets out a low chuckle.

“Children are comfortable in their environment,” Mills said. “I just become part of that environment.”

Mills said one of the downsides of the job is meeting so many people but not getting to know them well. He wonders what kind of high-schoolers the kindergartners become.

“I have a wide-angle view of everything, without an in-depth look at anything,” he said. “I know everybody in one way, but nobody in all ways.”

Even after Mills’s nearly 50 years at work, Marshall described him as agile and quick on his feet.

To get good shots, he squats down in a froglike position — so low, kindergartners tower over him.

Mills admitted his knees are worn.

“I squat. I duck around. I get up and look down,” he said. “I’m always moving.”

There have been a few times when Mills said he considered retiring. He said the school system offered to buy him out in the ’80s. And everyone thinks about it when they turn 60, he said. Mills will be 73 in June.

It will be nice to find something new to do, he said. He has always enjoyed painting and traveling. Maybe he will put his scuba-diving certification to use, he said.

He hopes the school system will use his archive; he wishes he had time to create a public online searchable inventory for alumni. For now, his images remain scattered and out of order in the back room of central office.

He said he isn’t sure anyone will ever put them to good use.

Looking through the images he shot that day, Mills stopped at one he liked.

A boy was reading with his teacher, his mouth open wide with excitement and his arms spread wide in the air.

“Look at him,” he said. “He is really having fun.”