The abstract photo - developed by an international avant-garde of artists at the beginning of the 20th century, such as Man Ray, László Moholy-Nagy, Paul Strand, Alwin Langdon Coburn - has hardly been perceived as an independent form of image and art. It represents a kind of counterpoint to the realistic-depicting photo and refers to the group of photographs that are not directed at a tangible object: an independent field of fine art with specific content, forms and functions. The artistic and scientific basis of this publication is formed by exhibitions, lectures and discussions at the 21st Bielefeld Symposium on Photography and Media at the Bielefeld University of Applied Sciences. The declared aim was to contribute to increasing awareness of the art of abstract photography. The focus was not, as has been the case up to now, on the photo as a medium, i.e. not on what and how it makes something visible, but on what it "is" visible: the "visibility of the image".