Some leading lights of Chicago documentary gather Wednesday to celebrate the 20th anniversary of Columbia College’s Michael Rabiger Center for Documentary Film.  A 5 PM panel discussion features documentarians Tod Lending (who garnered an Emmy award and Oscar nomination for his public housing doc Legacy); Michael Rabiger, Doc center founder and author of the canonical Directing: Film Techniques and Aesthetics; Judy Hoffman, who shot Howard Zinn: You Can’t Be Neutral on a Moving Train; Russell Porter, current Columbia documentary chair and founder of the Melbourne Documentary Group; Suree Towfighnia, director of Standing Silent Nation, about a Lakota Indian fighting the DEA for the right to grow industrial hemp on his South Dakota reservation, and student Arlen Parsa.  Rabiger, Columbia’s emeritus film chair, founded the center, and Towfighnia ran it for several years.  It’s free, at Columbia College, 1104 S. Wabash, Room 407.  A reception precedes the panel at 4 PM.  Films by current and former Doc Center students screen at 6:15, including this one by Chris Ottinger and Lem Huntington: