MICHAEL SNOW's Wavelength (1967) is a remarkable, 45-minute inch-by-inch zoom that starts as a shot of a living room before closing in on a hung photograph of the sea. As you get closer to the waves in the photo, you start to feel a sense of motion, a shifting of your perspective on everything. "Wavelength" is the first of five minimalist films being shown at the National Gallery's East Building auditorium, Saturday at 2. It's followed by Snow's One Second in Montreal (1969); Ernie Gehr's Serene Velocity (1970) and Eureka (1979); and Paul Sharits' T,O,U,C,H,I,N,G. (1968). Admission is free.

Friday at noon (free) at the Baird Auditorium (Natural History Museum) it's Umbanda the Problem Solver (1977), the 52-minute story of Umbanda, a modern cult founded in Brazil in the '20s and drawn from African roots. It blends Roman Catholic faith with belief in spiritual possession. John Homiak, from the Human Studies Film Archives of the Museum of Natural History, will introduce it. Call 357-2700.

Catch a trio of screenwriter Ben Hecht movies -- Gunga Din (1939), Boy Meets Girl (1938) and Actors and Sin (1952) at the American Film Institute this weekend. "Gunga Din" (Hecht and Charles MacArthur wrote the original story) shows Saturday at 3, Sunday at 6; "Boy" (written by Bella and Samual Spewack but supposedly a story about the Hecht/MacArthur team) and "Actors" (scripted by Hecht from two of his short stories) are double-billed Saturday at 8 and Monday at 8:45. This week at the AFI, you can also see the winner of the Maya Deren Award (for avant-garde films), Bill Viola's 1986 I Do Not Know What It Is I Am Like (Wednesday, at 7, AFI screening room, third floor), an investigation of connections between the human psyche and animal consciousness. Thursday at 8:45 marks the Washington premiere of Theo Angelopoulos' The Beekeeper (1986), with Marcello Mastroianni in the title role. Admission at the AFI is $4.50 ($3.50 members). Call 785-4600.

Friday (7:30, free) at the Library of Congress' Mary Pickford Theater, it's Dreamboat (1952) with Clifton Webb; Monday and Tuesday, Robert Aldrich's The Big Knife (1955); and Wednesday and Thursday, Vincente Minelli's The Bad and the Beautiful (1952). Call 287-5677 to make a reservation (seating is limited).

Tuesday at 8 (and marking the first anniversary of Andy Warhol's death), Gerard Malanga, a close collaborator of Warhol's for many years, will show two documentaries giving glimpses of Warhol's world. Andy Warhol: Portraits of the Artist as a Young Man (1965), directed by Malanga, is a series of Warhol screen tests. The Gerard Malanga Story (directed by Warhol) is a sequence from Warhol's 1966 The Chelsea Girls. Admission, at the Hirshhorn Museum auditorium, is $7.50 ($6 members). Call the Smithsonian Resident Associates at 357-3030 for tickets.

The Capital Children's Museum will teach students (grades 7 to 12) to make animation videos. The course lasts six weekends, from March 5 through April 23 and costs $200. To register call 298-7545.