Equivalent Abstraction: Roma Window, is another dramatic pairing of photographs and drawings where the camera looks at the position of the setting sun coming through the window; but instead of the sun descending toward the horizon, it was the mullioned window that moved up and out of the picture frame.

- Pepe Karmel, 2014

The image unit upon which she based Equivalent Abstractions is a corner in an empty studio that is illuminated by two bands of light, substanceless forms that imply the unseen existence of apertures into the otherwise empty space. For the 1974 Biennial at the Whitney Museum of American Art in New York, Zimmerman installed 15 photographs of this image taken sequentially over a period of time during which the positions of the bands of light moved and their shapes changed. Directly below the row of photographs, Zimmerman installed a corresponding row of seemingly identical images rendered by hand as graphite drawings. Hung one above the other, the similar images challenged the viewer to distinguish between the supposedly 'objective' medium of photography and the supposedly 'subjective' medium of drawing.  The work as a whole presents a provocative dialogue between alternative images and the reality that they represent.

-Charles F. Stuckey, 1982