The Corcoran Gallery of Art -- breaking ranks with other major Washington museums -- is about to charge admission for "selected exhibitions."

Director Michael Botwinick yesterday announced that "a nominal admission charge" -- $1.50 for adults, and 50 cents for senior citizens and students -- will be imposed on "L'Amour Fou: Photography and Surrealism," which opens Sept. 14.

Four other exhibitions there -- "Niagara" (Sept. 21-Nov. 24), Jonathan Borofsky (Dec. 12-Feb. 2), "The Indelible Image: Photographs of War, 1846 to the Present" (April 26-June 22) and one additional exhibit not yet selected -- also will be subjected to the new entry fees.

Admission to the gallery, to its permanent collection and to other shows on view there will remain free.

Other institutions in London and in Paris, Chicago and New York, long have charged for tickets to their special exhibitions. But Washington's museums, both federal and private, have managed to avoid imposing such fees.

"Ours are deliberately modest," said Botwinick, "and we hope they won't keep people away. In New York, admission fees of $4.50 don't significantly affect attendance." Botwinick served as director of the Brooklyn Museum before coming to the Corcoran. "We live in a world where people, even in Washington, cheerfully pay $50 for a ticket to the opera," he added.

"These fees," said Botwinick, "were imposed reluctantly. The alternative was a really serious cutback in our exhibition schedule."

The Corcoran expects to raise only $35,000 in admission charges in fiscal 1986. That is less than 3.5 percent of the fiscal year's exhibition costs, which, said Botwinick, will be $1,072,550.

Last month, the Corcoran's trustees approved a total expenditure of $3.1 million for fiscal 1986. An operating deficit of $254,000 is projected.

Until 1979 it cost $1.50 to enter the Corcoran, but that charge was lifted when Dr. Armand Hammer, chairman of Occidental Petroleum Corp. and a Corcoran trustee, gave the museum nearly $1 million to offset admission fees. The next year, admissions rose significantly. Corcoran board chairman David Lloyd Kreeger noted at the time that dispensing with admission charges was what the Corcoran had "needed most."

"We're not competitive with the other museums," Kreeger had explained to Hammer. "We charge admission and most don't."

On April 19, 1979, an engraved marble tablet was publicly unveiled at the Corcoran's front door. Its fresh gilded letters, large enough to be read across the street, spelled out the word "FREE."