Art reference books (encyclopedias, dictionaries, etc.) are shelved with the main collection and are borrowable. They are good sources of background material on art history, fine arts, photography, etc.
On this page is a selection of online reference works from Oxford University Press.
This catalogue search in Title Keyword shows how to find reference works on photography:
photograph* (dictionary OR encyclopedia*)
NB: The asterisk (*) functions as a wildcard, retrieving books with photograph or photography in the title.