Though there’s never even been a good name for it, American “experimental” or “avant-garde” filmmaking has been one of the most vital and transformative movements in the history of the medium. Since its inception in the 1930s, makers of TV commercials, music videos, and Hollywood features have been influenced by or even borrowed directly from experimental work. But more important, it has redefined the possibilities of the medium and the whole relationship between viewer and screen. Confronted with complex and paradoxical formal structures that call attention to themselves, the viewer becomes a more active participant in a journey with many possible destinations.

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The movement’s founders, from Deren and Anger to, a bit later, Brakhage, seemed to be making films as a way of saving themselves—using cinema to decide whether, and on what terms, they could go on living. Grants for such work were virtually unknown, and impassioned filmmakers scraped together funds however they could. In 1966, colleges began hiring avant-garde filmmakers to teach, and that trend grew; today, many films and videos by younger makers in festivals are in fact student productions. Predictably, many of these lack the urgency of earlier work, and some are just academic copies of past masterpieces. At the same time, making films is now much easier, which has encouraged an explosion of variety and, along with plenty of mediocrity, excellent work from diverse voices.

The videos by Gehr and Jacobs are both very strong, exploring similar terrain and, like many experimental films, offering the viewer alternative ways of seeing. For New York Lantern (Tue 6/16, 8 PM, Gene Siskel Film Center), Gehr rephotographs century-old magic lantern slides of New York, sequencing them in a way that opens up space. Often he’ll cut from figures gazing offscreen to emptier and more expansive locales, and there’s a stretching effect that suggests the world is too vast to be contained in a single rectangular image. Because the photos are very old, this evocative work also gives a sense of stretching back in time. In The Scenic Route (Thu 6/18, 7 PM, Nightingale), Jacobs uses selected frames from an old MGM romance, The Barbarian (1933), punctuating them with the flicker of a black screen and moving in on the image, or slightly sideways. These small changes open up vast depths and create the illusion of constant motion in every part of the frame. Jacobs has called his related live performances “Nervous System” pieces, and indeed the viewer’s whole sensorium is activated here: every segment of seemingly inanimate landscape seems to crawl with some strange form of life.

Having long groused about the dearth of great new experimentalists to emerge since 1966, I’ve come to understand that many young filmmakers no longer aspire to greatness in the old sense—creating synoptic masterpieces like Brakhage’s The Art of Vision (1965) or Peter Kubelka’s Unsere Afrikareise (1966). For some, this may result from the antipatriarchal, anticolonial, antihegemonic rhetoric common in the film theory of the 1970s. Simply put, many newer artists consider it hubristic to assume we can understand the world.

Tue-Sat 6/16-6/20, Chicago Filmmakers, 5243 N. Clark; Gene Siskel Film Center, 164 N. State; and Nightingale, 1084 N. Milwaukee; $8-$9, discounts for students and members of Film Center and Chicago Filmmakers, 773-293-1447, chicagofilmmakers.org.