Robert Smithson's photography is commonly associated with conceptual art and its watershed critique of the apparatus's documentary mode. On this basis, interpreters like Douglas Crimp, Craig Owens and Jeff Wall have all positioned Smithson as a key precedent to the expanded field of lens-based practice, keyed to the complex concept of the 'picture' that emerged following the artist's death in 1973. However, a careful review of the artist's work and writing reveals that his implicit theory of photography could also be meaningfully described as Minimalist - attuned to this quasi-sculptural movement's concerns with the clarification and renewal of spatiotemporal perception. Smithson's 1969 travelogue, 'Incidents of Mirror - Travel in the Yucatan', for instance, sets up a number of pointed equivalences between photography, Minimalist sculpture and select ancient Mesoamerican ritual objects designed - according to Smithson's understanding - to expand perception onto new planes of space and time. In recent years, scholars such as Walter Benn Michaels have advanced the idea that Minimalism's problematics offer key insight into late twentiet - century photography's foremost questions regarding the nature of this technology and its presence effects, in particular those that have long been associated with its indexicality. As this article demonstrates, Smithson's camera work engaged meaningfully with these same problematics, evincing a decidedly materialist yet radically expansive new conception of photographic picturing.