This article is written in response to the 2015 Prague Quadrennial and considers some of the difficulties inherent in disseminating the active role of light beyond performance. Building on Hannah and Harsløf’s notion of performance design as both ‘a doing and a thing done’, which is drawn from Elin Diamond, I consider the active functions of light in performance, and the challenges in representing these through exhibition. Drawing from my work as both a practitioner and a researcher, I offer a definition of ‘scenographic light’ as light that contributes independently to meaning in performance, listing three formative functions that detail its dramaturgical, rather than strictly aesthetic, affectivity.