LOS ANGELES (AP) _ Producer Nicolas Noxon acknowledges that telling the story of 100 years of the National Geographic Society presented a few sticky problems.

First of all, how do you get a century of exploration around the world, and in recent years out of this world, into a 90-minute documentary?

''We adopted a pretty pragmatic attitude,'' said Noxon, whose production of ''The Explorers: A Century of Discovery'' is his latest for National Geographic. ''The formula I worked out was that we would put in film on all the important things from the past 100 years and leave everything else out.

''Once I resigned myself to the coffee-table concept, once we got comfortable with that, it worked out pretty well. If we applied too rigid a test we'd leave out things we wanted in. We came up with 'The Explorers' for the title. If we strayed too far from that we weren't true to the theme.''

Noxon also faced the problem of keeping it from becoming just a cut-and- paste job.

''One of our dilemmas was that after all the musts we didn't have much time for electives,'' he said. ''Certain things just had to go in. We wanted to add some new film, but it was very limiting.''

New film for the 100th anniversary documentary includes a sequence on mapping the sky at Mount Palomar and a look at the Nova Scotia home of Geographic founder Alexander Graham Bell.

Appropriately, ''The Explorers'' will be telecast on Columbus Day, Wednesday, on PBS.

The show is largely told with archival photographs and film, much of it never before seen on television. Associate editor Terry Koenig, an Emmy winner for ''Secrets of the Titanic,'' worked closely with Noxon in putting the film together. Among the highlights:

-Conquest of the North Pole by Robert Peary, and Richard Byrd's flight over the South Pole;

-Exploration of Alaska's Valley of 10,000 Smokes in 1917, the first Geographic expedition to be documented in motion pictures;

-William Beebe's descent a half-mile into the ocean depths in a bathysphere;

-Harrowing exploration of the stratosphere in a hydrogen-filled balloon by Army Air Corps officers in 1934; and

-A 1931 French motor expedition from Beirut to Peking, including an attempt to drive across the Himalayas.

''I came here in 1960 after doing some educational and institutional films in Washington,'' Noxon said. ''I went to work for David Wolper in 1965, when he was doing documentaries. I fancied myself a documentarian, and Wolper was like a rocket then. I started doing the Geographic specials with Wolper. The first one I did was 'Voyage of the Brigantine Yankee.' The next one I did was 'Dr. Leakey and the Dawn of Man.'''

Noxon left Wolper after six years, but then returned to do more Geographic specials. In later years, he produced the specials for WQED-TV in Pittsburgh. Noxon recently joined ABC-Kane Productions, founded by Dennis Kane, former head of television for the National Geographic Society, in association with ABC.

He has made documentaries on wildlife, early Hollywood, diving for Spanish treasure, transatlantic liners and many other subjects.

''It's amazing what television's been willing to deal with,'' he said. ''Those of us in the West have rarely succeeded in placing news-oriented shows with the networks. We were able to get in with the wildlife shows. In 1966, I was able to talk about ecology, which was certainly an unknown word then, in a show about the grizzly bear. We were able to offer the hard idea that the grizzlies were disappearing and were worth saving.

''I got thrown out of Kenya for a show on the vanishing elephant. That was another unpopular idea. Elephants eat the same food as people, and people kill the elephants. What can we do? I don't think we've answered that yet.

''But think by protecting their monopoly on documentaries the networks have missed a lot. Dennis' company is the first semiautonomous documentary production group started by a network in many years.''

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