Leave the diaper bag; bring the breast pump. Backpacks and fanny packs are out of bounds. Cameras and binoculars are OK if they’re not in bags.

These are some of the new NFL restrictions on fans that will make a Metrodome debut Friday at the Minnesota Vikings’ preseason opener. Adopted in May by the NFL Committee on Stadium Security, the rule bans purses, except clutches that are roughly the size of a hand, with some medical exceptions and clear bags allowed.

The purse ban adds a new security restriction at large Twin Cities events. The Vikings will now have a security perimeter around the Metrodome that will check for contraband bags and create a buffer for the ticket gates. It’s a dramatic move — even U.S. presidents allow spectators to carry bags to their highly controlled visits.

The tighter restrictions come five months after bombs in backpacks went off at the Boston Marathon finish line, killing three and injuring more than 200 spectators.

Previously, fans who wanted to bring in bags were simply required to allow security to peek inside.

The Vikings say the change will upgrade gameday security, but at least one expert said he doubts separating fans from their purses will do much to enhance security. And some women balk at the idea of giving up their ubiquitous bags.

Jeff Anderson, director of communications for the Vikings, said the Boston bombings were just one factor in the change. “The NFL reviews policies every year to try and improve,” Anderson said, adding that some colleges already don’t allow bags at games. “It’s strictly about safety. It’s not convenient for anyone.”

The NFL and the team “strongly encourage” fans to leave all bags at home, although they will make some allowances. Any bag bigger than a clutch has to be clear, no taller or deeper than a foot, and no more than 6 inches wide. The logo must be no bigger than 4.5 inches tall and 3.4 inches wide. (The Vikings will send conforming logo totes to season-ticket holders.) Or each fan can carry one single-gallon plastic Ziploc-style bag.

Blankets can be tossed over shoulders and brought in — although that might be more significant for fans at Soldier or Lambeau fields. Each gate will have a separate entrance and guard for those seeking exceptions to bring in medical equipment.

Anderson insisted that no specific threat drove the change. “I certainly would rather be proactive on the front end,” he said.

For the first few games, Anderson said, security will have a nearby storage facility for fans who mistakenly bring forbidden bags to the gate, but that option will go away after a few games.

What about all that stuff?

Kim McCollow of Minneapolis was cool to the idea of leaving her messenger-sized purse behind. “You feel kind of lost without it,” she said. McCollow couldn’t identify anything in particular she needed, but said, “There’s just bulky stuff that I like having with me.”

She and others wondered about parents who need supplies for babies or kids. “You never know what you’re going to need when you have kids,” McCollow said.

Neither she nor others embraced the prospect of carrying a see-through purse.

McCollow called it a “weird” idea while Dana Mangnuson of Minneapolis pointed out that women need privacy.

“You’ve got Motrin, tampons and pads — you don’t necessarily want everyone to see that,” she said.

Mangnuson, who is a Type 1 diabetic, always has at her side a bag stuffed with juice boxes, her glucose monitor and sugar tablets.

Despite the policy’s exception for medical needs, Mangnuson said it’s still a worry that she would run up against a security agent who doesn’t understand her needs.

International security consultant and retired Northwest Airlines Capt. Steve Luckey said he has doubts about the need for the new rules. The key to stopping terrorism doesn’t lie in searching purses, but spotting intent by monitoring the news and chatter, he said. Most important, he said, is training security personnel to spot unusual behavior. “The Israelis are masters at this, and they’ve never had a hijacking on El-Al” airlines, he said.

Luckey said the desire to tighten security in the wake of the Boston bombings is understandable, but apolitical sporting events and concerts haven’t been major terrorist targets.

“I think you get to the point where you restrict things and it’s negative, like taking your shoes off at the airport — it’s stupid, absolutely stupid,” Luckey said.

For now, the bag ban is unique to the NFL. At Minnesota Twins games, spectators can bring in purses and even food, which isn’t allowed at NFL games. “We have a lot of female fans and male fans who like to bring a bag to the game,” said Twins President Dave St. Peter.

Target Field, which opened in 2010, has higher-tech security cameras and monitors than the Metrodome. Dogs trained in detecting explosives regularly sweep the ballpark. “There’s no doubt that security is going to continue to be a huge priority,” St. Peter said. “To the extent changes are made, it will further restrict” things.

The NBA and the Minnesota Timberwolves ban backpacks, briefcases and duffel bags, but allow purses after an inspection at the entrance.

Luckey said businesses have to watch how far they go both for customer experience and effectiveness.

“In our culture, we’ve been pretty free and fortunate for many years, and vigilance has to be higher than it has been before,” he said.