Although unsatisfactory in many ways, the ABC News Close-Up "Lights, Cameras, Politics," at 8 tonight on Channel 7, is one of the toughest looks television has ever taken at itself. For all the rank cant and occasional irrelevancies in the program, it flips into the mainstream certain doubts and fears about TV's effect on the political process that TV has previously given little attention.

Richard Reeves wrote, and Ann Black and Tom Priestley produced, the one-hour report, with Reeves as on-camera commentator voicing some popthink about TV that is practically a decade old: "Face it -- television is pictures," "Television was creating a new reality," "Television is more than a medium; it's an environment," and blah blah blah.

But we also get a crisp analysis of TV's role in political campaigns, and appropriate complaints about its priorities from the likes of Jerry Brown, who says, "In a sense, you might say if a person isn't on television, they are a political nonbeing. They do not exist for the voter even if that voter meets them in person."

And candidate John B. Anderson, who says that in order to get his kisser on TV, "we've made many detours and traveled many extra miles."

Unfortunately, the program suffers from a television tendency it doesn't investigate -- the zeal to be zippity and scattershot with information, to chop it up into little nuggets and abandon a subject the instant you've brought it up. It was hardly necessary, either, for Reeves to sink back into the history of the medium and even dredge up the name of one of its investors, Philo T. Farnsworth.

Television is remodeling American politics to suit its own peculiarities as a medium, Reeves says. When you think about the thesis, it sounds alarming terrible, a one-way ticket to Alphaville or Orwellia. One the other hand, television is our national town square; it's the bulletin board in the hallway, the morning paper and a phone call from Aunt Milly rolled into one, so why shouldn't everyone in politics be doing their darnedest to win its attention?

A segment on political commercials includes instructive or hilarious highlights from past campaigns -- a roaring movie-trailer tribute to "The Man From Abilene," Dwight D. Eisenhower; the man from Plains, Jimmy Carter, and Tony Schwartz's famous, short-lived anti-Goldwater ad for Lyndon B. Johnson in which a little girl pulls the petals off a daisy until the H-bomb explodes, blowing her to kingdom come.

Among those interviewed are Walter Cronkite, CBS News President Willliam Leonard, ABC News President Roone Arledge and Robert Dole, griping that one network that he doesn't name gave his entire campaign only 20 seconds of air time.

NBC News refused to cooperate with the producers in any way beyond permitting a few remarks by executive Richard S. Salant. NBC's position, a spokesman there says, is that it's not in business to help the competition -- a pretty petty and churlish attitude, but understandable when you consider that ABC's "World News Tonight" has overtaken the NBC "Nightly News" in recent Nielsen ratings.

Roone Arledge, as it turns out, doesn't like the show, either. "I don't think it's the finest thing ever done on television," he said recently. "I have no quarrel with Reeves' conclusions at all. But my personal opinion is that the program is a little shallow."

This is a tribute in a way both to the show and to Arledge himself. If he had loved it, it probably wouldn't be as critical as it should have been. But the fact he's putting it on the air -- and claims to have stayed completely away from it during production -- is a sign that ABC News is growing up fast.

Reeves decided to end the show with a bombshell, and like a lot of what we see in TV news, it may be more blinding than illuminating:

"The men who wrote the Constitution of the United States deliberately constructed an intricate set of checks and balances. They wanted to slow down the process of government. They wanted democracy to wait out the passions of the moment. Nothing could happen until the crowd dispersed, until the job went home. Now the mob is at home -- watching television."

A trifle patrician, that sentiment and on the clergical side. But much of what's said in "Lights, Cameras, Politics" is not only food for thought, but health food, as opposed to TV's usual Triscuits and Ho-Hos. There is much to argue with here, and a little to scoff at, but the program makes a sublimely timed preface to the Circus Maximuses from Detroit and New York that are still to come.