Jonathan Crary has an interesting argument about photography in his Techniques of the Observer: On Vision and Modernity in the 19th Century ---- that what principally matters regarding vision is not its biological or physiological truth but the degree to which and ways that vision is located in history and historical processes. Vision is historically constructed. Crary places models of the spectator in the centre.

Crary suggests that the camera obscura was a dominant metaphor for human vision as well as a crucial and consistent representation of the relation of a perceiving subject to an external world. In this visual paradigm or regime Subject and world were understood to be pre-given, separate, and distinct entities. As a consequence the act of seeing was regarded as both passive and transparent to the world being seen, and was in that sense an act sundered from the physical body of the observer. The Lockean account to ideas imprinting themselves on passive minds is reworked in terms of photography offering a mechanical and mass-produced form of exchangeable truth.

According to Crary around 1800 one finds a 'vast systematic rupture' in the history of vision which marked the end of the reign of the camera obscura as the dominant paradigm of knowledge and truth in the nineteenth century, in which the observer and camera obscurer are bound together by a single point of view; the camera is an apparatus fundamentally independent of the spectator and the camera a transparent intermediary between observer and world. Documentary photography works within this visual regime.

Crary argues that there was a simultaneous development of a modern and radically different type of optical and epistemological figuring and he insists that optical devices are 'embedded in a much larger assemblage of events and powers'. The advent of photography was one technological development that altered the entire episteme for viewing art and images. It commensurately altered human consciousness.He argues tha the meaning of subject-object relations in general has been totally transformed during the shift from Classical to modern. If the meaning is different, then it follows that the objects must be equally different.