Actors celebrate their own profession

''Mickey Rooney and Judy Garland can't put on a musical show in the barn anymore - the barn has been converted into a condominium.'' That's the kind of change that has taken place in the acting profession in the past 50 years, says Edward Asner, president of the Screen Actors Guild (SAG). We have this, and more, in a two-hour tribute to the guild, its members, and the entire acting profession, entitled The Screen Actors Guild 50th Anniversary Celebration (CBS, Tuesday, 9-11 p.m.). It's like a private party by and for actors - with the public invited to eavesdrop.

The fact that the show is a Smith-Hemion Production is enough to cause knowledgeable TV viewers to pay attention - this team has produced some of television's most remarkable musical programs. The broadcast makes no pretense at being anything other than what it is - a salute to the world of movie and TV actors, and especially to the union that has brought them some measure of dignity and equity from their labor.

The special begins with what might seem to be a grand finale - a rousing song titled ''I'm An Actor . . . Here's My Card,'' in which hundreds of guild members , recognizable and unknown, take part. In this number, as well as in other numbers throughout the show, there are pertinent film clips from new and old movies which help make the point of the film: that actors have been contributing to our society for a long time and still only a small percentage are able to earn a decent living from it. An especially clever and poignant production number points this up as actors in temporary, sometimes menial, jobs sing about ''What I Do for Love.'' Mr. Asner declares, ''Nobody ever said it'd happen like in the movies.''

But at the end of this special, despite current political differences, president Asner, with quiet dignity and respect, reads a congratulatory telegram from Ronald Reagan, the former six-term SAG president.

Although the ''SAG Anniversary Celebration'' is loaded with ''significant'' little speeches, tableaux, and dialogues, there are many light, entertaining moments - including a superb recital of the development of an actress by Cloris Leachman.

But the fact is that ''The SAG 50th Anniversary Celebration'' is basically a show about a labor union, a kind of 1980s ''Pins and Needles.'' Although you may be enchanted by some of its lightheartedness, behind the entertainment it is clear there is solid, serious resolve.

A chat with Edward Asner

''I would be delighted to shut up if everybody else who isn't an actor began to shout,'' says Ed Asner, better known as Lou Grant of ''Lou Grant'' and ''The Mary Tyler Moore Show.''

I have just asked him, over lunch at Mindy's, if it is true that he has lowered the volume of his highly publicized protests on US foreign policy in Central America. He is in New York to publicize his recent special (''Anatomy of an Illness,'' in which he plays Norman Cousins), as well as to do the SAG special (see above).

''If people want me to maintain silence because I am an actor, I should turn in my credentials as an American citizen. We crow mightily about our great freedom of speech in this land, and yet there is an unbelievable paucity of it in this country. The only reason I started shouting was because I was frustrated to see the things I believe in not printed, not talked about.''

Mr. Asner, who hasn't worked very much since ''Lou Grant'' was canceled by CBS in the midst of a political controversy and falling ratings, says that his political outspokenness ''has not stimulated employment. It may have kept me au courant, but it didn't get me many jobs.'' Right now, he is hopeful that ''Off the Rack'' (his new series with Eileen Brennan about the garment industry) will be picked up in midseason 1985 by ABC. He also has hopes that a miniseries on the life of Ulysses S. Grant, with Asner portraying Grant, will be made soon.

Mr. Asner is eager to talk about the SAG show: ''It's probably the first TV special ever about a union. That's a triumph because of the difficulty of getting the show on. People didn't want to appear at first because of the recent controversial election in the union (which Asner won).'' Asner represented the left-of-center membership, with the right-of-center supported by ex-SAG president Charlton Heston.

''All we wanted to do was say, 'Here we are, here's what we are all about, here's what the actors' union is.' We also wanted to further the theme that actors are workers, too.''

Now that the battle is all over, does Asner believe that ''Lou Grant'' would have continued on CBS if Asner's outspoken politics had not become an issue?

''I think the upheaval, the threats of boycott coupled with a five-point drop in (the ratings), permitted cancellation of the show. At that time, a few years ago, the 27 (percent ratings) share we got made the show an iffy item. Now, it would be a top-10 show. So maybe we were merely the herald for what was to occur in commercial television. But my great regret was that CBS, such a prestigious leader in television, didn't put any effort into saving a show they had declared such pride in heretofore.''

Is it possible that ''Lou Grant'' can be revived?

He shakes his head. ''No. It's dead. It was never a blockbuster in terms of ratings, just prestige.

''It was a halcyon five years. I did not have joy in doing 'Lou Grant' - it was hard work - but I had joy in knowing what hard work accomplished. The achievement of the first true newspaper story on TV - a least the closest approximation ever. We dealt with issues. I think we had a better ensemble caste on 'Lou Grant' than we even had with Mary (''The Mary Tyler Moore Show''), and I never thought that could have been accomplished. But it's over now and I don't think we can go back to that.''

Mr. Asner says that, if he seems a bit quieter these days, perhaps he is suffering from ''battle fatigue'' in the struggle to make his dissenting opinions heard.

As an actor or as an American?

No hesitation. ''As an American. The battle is never ending. That's what happens to people in this country. They fight the battle of defending civil liberties for a while. Maybe they get burned, maybe they don't. Then they retire for a while. And then, hopefully, others take up the cudgels. But you never have enough troops.''

Mr. Asner says that he recently tried to enlist Shirley MacLaine in one of his political crusades. ''She told me she now thinks it has to come from the people, not from actors. However,'' he insists, ''somebody has to come along to plant the seed that the people can water and cultivate and harvest. It sure ain't going to spring up spontaneously. There has to be a big wind blowing the seed in the direction of the people.''

So Asner thinks of himself as a big wind. Some other people might agree, the interviewer jokes. But Asner is not to be put off by humor.

''Yes. I like to think that I contributed to the big wind in terms of the American press and people recognizing the misinformation, disinformation, paucity of information, on Central America. And now, too, in helping to spread the word about the Screen Actors Guild.''