For more than two years, the White House remained silent as photographer Ansel Adams wrote a letter a day to newspapers and congressmen decrying President Reagan's "disastrous" environmental policies and his interior secretary, James G. Watt. Adams warned of "a catastrophe," "a tragedy" and "the Pearl Harbor of our American Earth."

Then Adams went further. He said in an interview in the May issue of Playboy: "I hate Reagan."

"That apparently got to him," Adams said.

The telephone call came from Michael K. Deaver, one of Reagan's top assistants, shortly after the magazine hit the streets. "He said the president walked into his office and said: 'I want to talk to this man, Adams, to find out why he dislikes me so much.' "

They finally met Thursday in Reagan's suite at the Beverly Wilshire Hotel in Beverly Hills, Calif. Reagan had wanted Adams to come to the Oval Office, but the photographer and conservationist, 81, said he wasn't strong enough to make the trip.

The talk was scheduled to last for 15 minutes, but to Adams' amazement, it went on for 50, as the two men discussed the issue that divides them most: the environment.

"We really are not as far apart as you think we are. I've always been an environmentalist," the president began, as Adams recalled the conversation. He said Reagan recited for 10 minutes what he considered to be his environmental accomplishments.

Adams, whose activism and thousands of photographs capturing the nobility of nature have made him a patron saint of environmentalists, said he then delivered the sternest rebuttal he could muster, pouring out to the president his concern about national parks, wilderness areas, air, water and Watt.

"He was very amiable, very sincerely cordial," Adams said later. "He was a gentleman, he'd be a nice neighbor. But there is that stone wall when someone has a totally different concept of the world and it's very hard to break through. The man has certain fundamental opinions and is given the advice and counsel of people who have similar opinions and he'd like to believe it.

"It's like the sea wall. The breakers come in and crash and the water rushes over the wall but the sea wall remains . . . ."

The White House apparently saw the meeting through different glasses.

"Adams came in initially with strong concerns about the environment. His concerns were met head on and dulled," spokesman Larry Speakes said. "The president thoroughly enjoyed the meeting. It went according to plan and was most satisfactory."

Speakes said he believed that Adams, rather than the president, had sought the meeting and added that Reagan made no promises to Adams.

The meeting occurred as the administration is trying to defuse controversy over its environmental policies. It recently moderated its stand on acid rain and has taken several initiatives aimed at protecting the environment, including steps by Watt to end the killing of endangered bald eagles.

Deaver also put in a call recently to Jay Dee Hair, head of the National Wildlife Federation, the nation's largest environmental group, to talk out various differences.

After meeting with Reagan, Adams said, he immediately began to tape his recollections so he would have a record of what the president had said. He described the meeting in a telephone interview from his Carmel, Calif., home overlooking the a section of the Pacific coast that Congress has placed out of reach of Watt's offshore oil leasing program.

Adams' account provides an unusual look at the president trying to cope with a critic, and a critic trying to cope with the president.

"I told him Mr. Watt is the most dangerous element in the country today," Adams said. "I said: 'Mr. President, I respectfully suggest that you are being misinformed by Watt on much important information.' I expressed myself as forcefully as I could.

"He didn't say anything, really. He just said: 'Jim's got very strong ideas.' He still is thinking that he's a pretty good Joe." Adams said he was waiting for Reagan to mention his incendiary remarks made in the magazine interview, but the president did not even allude to them. Nor did he explain why he wanted to meet Adams except to say lightly at the outset, "We have some matters to discuss, don't we? Maybe about your friend, Mr. Watt?"

Although the men talked for 50 minutes, Adams said he did not feel they communicated. They sat only a few feet apart on a sofa in Reagan's suite, but Adams said he felt they were in different worlds.

The photographer would voice his concerns, he said; Reagan would respond with cordial generalities or a recitation of his conservation achievements as governor of California. Adams said he left more determined to fight the administration's policies.

Adams, an active environmentalist for more than 50 years, said Reagan was different from any president with whom he has discussed conservation.

"He kept telling me by all obvious indications he was right, but he didn't slap the table and say, 'You're wrong!' It would have been very rewarding if he had blown his top. That would have made it easier for me to get into specifics," Adams said.

"When I'd seen President Johnson, he had quite an aura of authority. I had the same feeling with Carter. With Ford, I felt the same thing. They all asked intelligent and very difficult questions.

"With Mr. Reagan, I found him amiable but not very imaginative. He just sat there. He has great ability to maintain a theatrical interest. You may think he's interested, but he may be far off. I had the feeling it was split attention.

"I got a feeling he doesn't have any fundamental interest or knowledge in the environment as a concept. I think he works on advice or recommendations. He's almost waiting all the time for human prompt cards. He never came back with a rejoinder like, 'What would you do?' Carter and Ford did that."

Adams said he could recall almost nothing substantive coming from Reagan.

"I can remember what Ford said. I can remember what Carter said. That was years ago, but even from yesterday, I can't remember what Reagan said. It was very general."

Adams said that he remains active in the Sierra Club and other environmental groups but that he was appealing to Reagan as "a citizen, free of organizational influence. It was in fact a personal statement, and I think I made that clear." Still, his positions match those of most environmental groups that have attacked Reagan.

Adams said he views Reagan and Watt as men who "know the cost of everything and the value of nothing." He said he believes they are squandering America's heritage by speeding up the leasing of coal, oil and other minerals beneath western lands. He said these policies so offend his reverence for nature that he could not bear to photograph the president or his ranch.

"If I were to make a photograph of him, I could not get my opinion of him out of my mind. It would affect what I saw, how I managed the photograph," Adams said.

Two things keeping him going, despite his weak heart, he said, are his pacemaker and his battle to stop Reagan and Watt.

For all his intense anger at them, Adams said he is hard-pressed to document widespread environmental damage from their policies. But he mentioned a proposed strip mine outside Bryce Canyon in Utah, development in potential wilderness areas throughout the West, and encroachment on the nation's last open spaces.

"The basic plans, the allocation of funds, the whole approach, has created more of a fear and a doubt," he said.

Adams said he urged Reagan to look at the environment as one "big picture" that needs to be protected as a whole--an approach that would call for the creation of more parks and wilderness areas, plus protection of clean air and water.

He said he focused much of his criticism on Watt's near-moratorium on acquiring new park land and told the president he had learned from "impeccable sources" that the morale of the National Park Service was plunging. Reagan answered, Adams said, by praising Watt's five-year program to repair aging park facilities such as roads, sewers, bridges and trails.

Adams said he also expressed concern about acid rain and charges of mismanagement and industry influence at the Environmental Protection Agency. He said Reagan responded by citing "strong scientific divisions" about how to combat acid rain and by saying former EPA administrator Anne M. Burford was "railroaded from her job."

"Well, what could I say?" Adams said. "I just said I thought the EPA was a scandal and there was tremendous damage."

Reagan's strongest response came, Adams said, when the conservationist suggested that the president "take $10 or $20 billion out of defense and put it into a crash program on magnetic and laser fusion. He raised his eyebrows on that, the defense cut."

When it was all over, Adams said, Deaver remarked that he had bought one of Adams' photographs--"Clearing Winter Storm"--years ago for $250 and had been "very pleased to sell it for $6,000." An assistant to Adams, who overheard the remark as the men walked out of the presidential suite, said: "I didn't have the heart to tell the man it was now worth $10,000."

Adams said he still is sorting out his thoughts about the meeting with Reagan, but that these things caught him off guard: Reagan is physically smaller than he appears on television, he was "a warmer man than I anticipated," and he was willing to listen.

As for himself, Adams said, "I was braver than I expected to be."