contraption in downtown Minneapolis which could perform automatically the four basic camera movements - pan, zoom, tilt, and rotation.  Various mirrors were mounted in front of the lens and, combined with the camera's movement, confound our sense of what's reflected and what's real.  More recently, in a group of tapes called Summer Salt, she utilizes the various mirrors and mechanical devices as well as preprogrammed switching to present images of the southwestern U.S. that once again pose questions about vision.  However, these tapes seem to be less programmatic, less cerebral than some of her Machine Vision pieces.  For instance, in Somersault (1982), a mirrored sphere is fastened a short distance from the lens, creating a fish-eye effect.  Steina becomes a contortionist, jumping, bending, and twisting her body in a humorous mock-gymnastic performance.

Until 1977, all of the machines the Vasulkas employed with the exception of the programmer - operated according to the parameters of analog electronics, in which changes in the signal - audio volume, video brightness - are interpolated as voltage changes that vary continuously.  An image or sound is produced through amplitude and frequency variations that are subject to distortion.  By contrast, in the digital mode the parameters of signal are sampled at discrete time intervals, and these samples are translated - through and analog-to-digital converter - into binary code.  When displayed, this code is transformed to discrete picture elements, or pixels, each one controlled individually or systematically by a computer.  Pixel size varies according to the amount of memory available: more memory capacity allows a smaller pixel size, thus providing a greater resolution.

In the mid-'70's, the implication of digital computers were considerable: not only was digital imaging more precise, but for Woody it offered a third model for imaging based not only on electromagnetic energy but on mathematical systems.  But in the mid-'70's computers were so complex and expensive that an extensive programming background was essential for anyone who wanted to employ them.  Moreover, getting an image on the screen was not too difficult but manipulating it in real time was.  Producing a recordable output was yet another stumbling block - a problem exacerbated by the fact that computer designers and video designers hardly communicated.

The Vasulkas began work on a digital system in 1976.  Don McArthur fabricated a prototype and Walter Wright wrote its first programs; both men had experience with computers. 37 But it was Jeffrey Schier, then a student at the State University of New York at Buffalo, who designed and built, with Woody, a more complex system called the Digital Image Articulator or Imager.  Because of the enormous time and energy required - by Steina's count, Woody soldered over 20,000 connections - all of the Vasulkas' effort in the late '70s were directed toward building the Imager.  (The tape Cantaloupe, completed in 1981, is Steina's documentation of the process.)  In 1977 and 1978 the Vasulkas made several tapes titled Update, which are visual summaries of their work with the Digital Image Articulator.

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