The Imax movie theater at the Smithsonian Institution’s National Museum of Natural History is set to close. (Smithsonian Institution)

The Imax movie theater in the Smithsonian’s National Museum of Natural History will close Sept. 30 to make room for an expanded cafeteria and exhibition space.

Museum officials say the Johnson Imax Theater, a 500-seat venue that opened in 1999, is usually filled to only about 20 percent capacity, while the nearby restaurant, one of the smallest of the Smithsonian cafeterias, is frequently overcrowded. Officials hope to complete the renovation in time for the reopening of the Fossil Halls in 2019.

“We want to do something to make people comfortable, and to allow them to spend more time in the museum,” said museum spokesman Randall Kremer. “With the Fossil Halls opening in 2019, we expect more visitors and we want to be ready for them.”

A group of 11 Imax documentary filmmakers is protesting the decision. In a letter to museum director Kirk Johnson, the directors and producers of such films as “Amazon Adventure,” “Everest” and “Into the Deep” have asked the museum to reconsider its plan.

“The National Museum of Natural History is the one place in the nation’s capital where children can enjoy the highest quality natural history exhibitions, collections and films,” they wrote. “It would be a shame to lose one of the most engaging and successful parts of this remarkable educational offering.”

The filmmakers question the museum’s priorities, especially at a time science appears under attack.

“In a world where nature is slipping farther from our grasp, Imax educational films have the proven power to educate, engage and inspire a new generation of scientists, environmentalists and defenders of our planet,” the filmmakers said. “We need to serve our children ideas … more than we need to sell them more food.”

Kremer said that the museum respects the opinion and work of the filmmakers but that its internal analysis shows the space could be better utilized. The museum attracted 7.1 million visitors in 2016 and sold 312,000 tickets to the Johnson theater.

“The problem here is [the theater] isn’t performing anywhere close to capacity and is not meeting the goals we set for it,” Kremer said. “We think the new restaurant will be more attractive.”

The Smithsonian operates two other Imax theaters, at the Air and Space Museum on the Mall and at that museum’s satellite space near Dulles International Airport. Those theaters screen space- and flight-themed works.