The crowd-pleasing art superstars may be holding court one floor up - at “Georgia O’Keeffe and Ansel Adams: Natural Affinities,” opening Saturday, May 30 - but before you wander O’Keeffe’s pink and orange abstractions of the Southwestern desertscape and Adams’ iconic prints, dare to stop in at “Looking In: Robert Frank’s The Americans,” on display at the San Francisco Museum of Modern Art through Aug. 23.

You’ll be drawn into this exhibition celebrating the 50th anniversary of Frank’s book, perhaps the most important and influential volume of photographs to make a mark on this country’s imagination. Organized by the National Gallery of Art in Washington, D.C., “Looking In” gives Frank’s iconic images their full due, detailing the process, the back story, and the book in all its forms. Assembled are vintage prints, a collage assembled by Frank in 2007 and ’08 touching on themes and his first edit, older series, international editions, a curious artwork in which Frank mutilated his original photographs, and a film made by Frank just for this exhibit.

The individual Americans photographs – still acute, evocative and courageous in their penetrating looks at segregation, inequality and injustice - are worth getting lost in, particularly the images Frank shot in San Francisco. In one, a callow John Garfield lookalike stares into space with a mixture of satiation, loneliness and shame, above a mosaic of soiled cafeteria dishes. In another, which Frank has described as his favorite photo for the unguarded hostility on his subjects’ faces, an African American couple looks back with barely concealed rage at the shooter, as they lounge on the grass of what looks like Alta Plaza Park in Pacific Heights. They seem to drift low in the frame as ivory edifices climb the hill above them.

Bibliophiles will appreciate the chance to peruse Frank’s contact sheets, the photographer’s application for Guggenheim funding (with edits by Walker Evans), and manuscripts of Jack Kerouac’s introduction. Fitting, too, that this tribute to a book that touched innumerable photographers, poets, artists and readers has inspired yet another volume: the handsome and comprehensive catalog published by the National Gallery of Art. Also a must for cineastes: through June 27 SFMOMA is showing Frank’s films, the medium the artist turned to after The Americans met with outrage in this country. His canonical 1959 avant-garde short, Pull My Daisy - a snapshot of the Beat Generation penned by Kerouac and populated by Allen Ginsberg, Gregory Corso, Larry Rivers, Alice Neel and others - will be screened along with the controversial and rarely seen Cocksucker Blues (1972), Frank’s feature-length documentary of the Rolling Stones’ 1972 North American tour, post-Altamont.

"Looking In: Robert Frank's "The Americans" through Aug. 23. San Francisco Museum of Modern Art, 151 Third St., S.F. Hours are Mon.-Tues., Fri.-Sun., 11 a.m.-5:45 p.m.; Thurs., 10 a.m.-8:45 p.m. Admission is $12.50, $8 seniors, $7 students, free for members and 12 and younger (free on the first Tues. and half price Thurs., 6-8:45 p.m.). (415) 357-4000, www.sfmoma.org.