Derges’s 1991 series "The Observer and the Observed" explored the relationship between object and viewer, and art and science. Propelling a jet of water through the air, Derges used a strobe light to capture the suspended lens-like droplets set against a blurred image of her own face. During the 1990s, Derges became well-known for her camera-less photographs—or photograms—of water. Using the landscape at night as her makeshift darkroom, Derges submerged large sheets of photographic paper in rivers, using a flashlight and the moon to create exposure.