Firstly, we need to unpack what is is meant by poetics. It is broader than poetry in that it implies a creative act that points to something beyond itself. This refers to poiesis or a bringing into being: an unending creative struggle to express that which conditions and informs our worlds of meaning and yet resists being exhaustively articulated in the terms of these worlds.
How does this conception of poetics relate to visual art including photography?
The starting point would have to be Kant, since it was he who first systematically outlined the logical grammar or conceptual machinery of aesthetics though his categorical separation of knowledge /truth as in the natural sciences, morality and aesthetic in modernity into separate domains. In the Critique of Judgement Kant acknowledges that scientific cognition excludes aspects of ourselves from its view of nature and that this must be accounted in other than cognitive terms.
He does this in terms of an aesthetics that is based on the imagination, autonomous art, intuition, aesthetic ideas, taste and the lack of concept. Kant, in other words, in inscribing art with the autonomous domain of the aesthetic relegates art and aesthetics to what is outside truth and goodness. Autonomous art is autonomous from truth and morality.
Art, therefore, is being understood in non-cognitive terms, has lost or being deprived of its power to speak the truth. It also means that language cannot completely represent aesthetic ideas. The aesthetic, with the early Romantics, is preserved as the sphere of meaning that cannot be subsumed into any other, such as those of scientific or economic rationality that have become dominant in modernity. Aesthetics protests its alienation in that scientific truth should not be the only conception of truth, starts to transform itself from within.
An example is Heidegger's conception of truth a-lêtheia, that is, “truth” conceived ontologically as historically-variable “un-concealment” or “dis-closure.” This refers to the idea whereby some things (or aspects of things) cannot emerge into the light of our intelligible worlds without others withdrawing into the background (which means that it is impossible for everything to take place in intelligibility all at once).