攝影能提供什麼有關現實之知識？如何讓觀看者更理解現實？影像與現實之間的關係又為何？本文以法蘭克福學派作為理論資源，並以「新紀實」類型作為探討對象，提出「再現」之外另一種以「認識」為目的之紀實攝影理論與實踐。該方式跳脫一般紀實攝影將照片作為「證據」之框限與「決定性瞬間」之標準，要求攝影者透過攝影影像拉開觀看者與現實之間的距離，打斷與現實之間的日常關係，而以採用質疑或否定之角度來思考現實、反思自身，把「現存的（現實）」視作「尚未（完成）的」。本文認為，紀實攝影的「美學」議題也是攝影認識論的問題；而知識社會學理論可作為紀實攝影認識論之對話對象，並幫助攝影研究者與實踐者釐清個人、攝影、觀眾，與現實之間的距離和關係。

What kind of knowledge about reality can documentary photographic image provide? How can photographers do to give viewers better understanding of the world? With critical approach of the Frankfurt School, this article discusses New Documentary tradition in photography and the relationship between photographic image and reality. The article states that the ‘representative’ function of photography can be replaced by ‘understanding’ one. To give viewers deeper understanding of the reality, photographers of New Documentary went beyond the limit of photographic image as evidence and the aesthetics of ‘decisive moment’; Instead, they used photography as tool to defamiliarize the viewers’ knowledge about the ‘existed’ world and the way they used to think about reality. The article regarded aesthetic theories of the Frankfurt School as valuable source in helping theorist as well as photographer to assess practices of documentary photography and to start dialogue between social theories and epistemology of photography.