Photographic recording has gained a key role in shaping contemporary experience—everyday and extraordinary. When brought into the art museum space, this photographic perception may challenge the institution, which has historically privileged quiet contemplation and appropriate manners, and governed the visitor body through written and tacit rules. How do art museums now accommodate two types of seeing—photographic and direct? How does the performance of the first type configure the visitor’s encounter with the artwork? Visitor photography is treated in this PhD research as a potentially destabilising mediator inside the art museum: it re-shapes both the experiential space and visitors’ relations with the exhibits. To explore this topic, ethnographic studies were carried out at four London-based art museums and galleries, supplemented by interviews with visitors and museum professionals—curators, educators, visitor experience managers, and invigilators. This research examines, firstly, how art museums are offered, through boundary establishment and maintenance, as out-of-ordinary spaces for experience. Close attention has been focused on the changed stance of art museums on visitor photography, which reflects a larger shift in the relationship between the institutions and the public. Secondly, scrutiny centres on how visitors live their visit bodily with picture-taking: how picture-taking is embodied by visitors through a series of movements; how the photographic process has to be bodily accommodated by visitors in general, whether they are taking pictures or not. Finally, examination focuses on how photography mediates visitors’ encounter with artworks in art museums or galleries so as to reveal the consequences and possibilities of experiencing artworks not through direct seeing but through looking at photographic images of artworks; not through the conventional museum manners constituted by moving-standing-gazing but through bodily investment in the form of picture-taking. The findings show that, art museums and galleries are socially shared spaces and that visitor photography has social consequences. On the one side, visitor photography has gradually become normalised in the gallery space in the form of changed museum rules — though still no in the curatorial planning. On the other side, picture-taking can be seen as competing with direct-seeing, given the limitations on visitors’ attention and time. It has become a popularly performed ritual through which visitors re-work their ways of seeing and their connection with artworks and museums. It is suggested that this altered dynamic between art museums, artworks, and visitors requires art museums to rethink both exhibition design and their roles as art mediators.