“If you turn your country into a totalitarian surveillance state, there’s always some wrongdoing you can prevent,” said Jay Stanley, a privacy expert with the American Civil Liberties Union. “The balance struck in our Constitution tilts toward liberty, and I think we should keep that value.”Police and private businesses have invested heavily in video surveillance since the Sept. 11, 2001, attacks. Although academics debate whether these cameras create significantly lower crime rates, an overwhelming majority of Americans support them. A Washington Post poll in November found that only 14 percent of those surveyed wanted fewer cameras in public spaces.

But the latest camera systems raise new issues because of their ability to watch vast areas for long periods of time — something even military-grade aerial cameras have struggled to do well.

The military’s most advanced experimental research lab is developing a system that uses hundreds of cellphone cameras to watch 36-square-mile areas. McNutt offers his system — which uses 12 commercially available Canon cameras mounted in an array — as an effective alternative that’s cheap enough for local police departments to afford. He typically charges between $1,500 and $2,000 per hour for his services, including flight time, operation of the command center and the time that analysts spend assisting investigations.

Dayton police were enticed by McNutt’s offer to fly 200 hours over the city for a home-town discount price of $120,000. The city, with about 140,000 people, saw its police force dwindle from more than 400 officers to about 350 in recent years, and there is little hope of reinforcements.

“We’re not going to get those officers back,” Biehl, the police chief, said. “We have had to use technology as force multipliers.”

Still, the proposed contract, coming during Dayton’s campaign season and amid a wave of revelations about National Security Agency surveillance, sparked resistance. Biehl is looking for a chance to revive the matter. But the new mayor, Nan Whaley, has reservations, both because of the cost and the potential loss of privacy.

“Since 2001, we haven’t had really healthy conversations about personal liberty. It’s starting to bloom about a decade too late,” Whaley said. “I think the conversation needs to continue.”

To that end, the mayor has another idea: She’s encouraging the businesses that own Dayton’s tallest buildings to mount rooftop surveillance cameras capable of continuously monitoring the downtown and nearby neighborhoods. Whaley hopes the businesses would provide the video feeds to the police.

McNutt, it turns out, has cameras for those situations, too, capable of spotting individual people from seven miles away.