This is all helpful enough, but one feels the absence of essays would do some work toward conceptualizing the material presented and Warhol's engagement with photography itself, in all its variability and idiosyncrasy. The rather underwhelming insights of Susan Sontag are the only ones cited here. One of the essayists, Ludger Derenthal, makes an aside that may touch upon one of the origins of the problem. He notes that it remains a focus of contestation whether the Polaroids and photobooth pictures are to be regarded only as source materials for silkscreen prints or as autonomous works of art. For the most part, the essays avoid tackling this problem, and instead presume that their task is to provide a framework for understanding the photos as works of art.
Few artists are more boring when treated thematically.
There were only a couple of essays that seem to me to help us start to think about the whole range of problems raised by Warhol's photographs, the way they actively resist being treated as art in a coherent way. Mark Francis makes a suggestive case for the specificity of Warhol's everyday photography. He argues that from the photobooths to the Minox, Warhol's interest was strongly indexical, participating in a modernist tradition the terms of which were articulated by Rodchenko, who identified the casual snapshot, accumulated in a documentary photofile, as the necessary form of the contemporary subject. Warhol left behind. For this reason, Francis wants to claim that the contact sheets are his most potent and unexplored legacy.