Those who know his gallery, and the art that he's been selling here since 1939, may be a bit surprised by Franz Bader's exhibition at the Phillips Collection here.

It is a show of photographs, though the Bader Gallery, unlike so many others here, has never had a photo show. The pictures at the Phillips are, at least in spirit, color field abstractions.That, too, seems unlike Bader. Though he showed Kenneth Noland and Gene Davis early, he readily acknowledges that he "missed the Color School." And though Bader, in the past, has loyally supported scores of local artists, here he is on his own. The photos at the Phillips are ones he took himself.

Most of them portray small details of nature - raindrops on a windshield, fallen leaves on water, the scales of a swordfish, shadows cast by leaves. "I try to see," says Bader, "the beauty others overlook."

He is not, by any stretch, a painstaking technicians. He owns only one camera and one lens, buys film at the drugstore, and sends it out to be developed. "I always make mistakes," he says, "I don' think about eexposures, I just look and shoot."

Bader is no master, but it is easy to forgive him. Walking in the woods, discovering the moss that grows on stones or the way sunlight dances on the ripples of a puddle, is for him a source of pleasure, and his pleasure shows. Bader will be 74 this month, but these are not an old man's pictures.

"Well, I am young," says Franz Bader, "I am starting my third life."

His first life, he explains, was the one he lived in Austria, Vienna, between the wars, was an imperial capital that no longer ruled an empire, a city of intellectual and social ferment. Bader was a partner there in Wallishauser, the city's oldest bookshop. He escaped Hitler in 1939, and his second life began.

Bader and his wife, Antonia, had searched through U.S. phonebooks writing to all Baders, hoping that some "relative" might help them get their visas. They were luckier than many. A Philadelphia schoolteacher responded, and helped Bader find "guaranteed employment" at the Whyte Bookshop and Gallery here.

The art shows he mounted there were given, for the most part, to unknown local artists (though he did give Grand Moses her first solo show). "Bader," writes Adelyn Breeskin of the National Collection of Fine Arts, "encouraged our local artists by showing their work before there were other places . . . He had been a major catalyst in the development of art appreciation in our midst." The Phillips calls its Bader show " a celebration for an old friend."

In 1971, Bader, now a widower, married Virginia Forman and his third life began. Returning to photography (he had taken pictures as a child before World War I), Bader began to travel to far-off lands.

The Baders (and his camera) traveled up the Amazon, to Kenya, Tanzania, Ethiopia, Siberia, Samerarkand, Tashkent. Pictures from his voyages - a white fog of mosquito netting, a pair of sleeping lions, a study of a carved Central Asian door - are included in his show.

Earlier this summer, the Baders took a camper for a 7,500-mile drive through the Canadian Rockies. "When I hear the birds sing, I feel the old idealism," says Bader. "The mountains were so beautiful that I'm afraid I took what I call 'tourist pictures.'" Bader has attempted, without complete success, to exclude "tourist pictures" from his Phillips show.

Bader's gallery, 2124 Pennsylvania Ave. NW, has long shown smaller prints and drawings whose images are odd, disturbing or fantastic. The pictures now on view there are etchings by the German writer Gunter Grass, who adds flies to his portraits, dead shrimp to his ashtrays, and fills his striking prints with penises and fish. Equally disturbing prints, by the Viennese Ernst Fuchs, are displayed in the window.

"Contrary to my reputation," says Bader, "I deeply love abstraction. And color is my life."

His 67 color photographs at the Phillips Collection will remain on view there unitl Sept. 25.