This is perhaps the most beautiful time in human history; it is really pregnant with all kinds of creative possibilities made possible by science and technology .  Jonas Salk’s quotation seems particularly pertinent to recent developments in imaging technology, which have provided both beauty and insight in equal measure. We can now manipulate biological systems, both genetically and otherwise, to introduce fluorescent markers, literally adding colour to our preparations. These advances have occurred in parallel with remarkable developments in microscopy technology, with novel means of illumination and light detection allowing imaging to be done in ever more inaccessible places, with ever improving temporal and spatial resolution. A critical step in the application of these new technologies though is to characterize their relationship to older ways of measuring phenomena. In this chapter, we describe some of our efforts to use Ca2+ dyes to follow network activity, and in particular the progress of epileptiform events through cortical networks. The conventional means of recording epileptiform events has always been, and likely will continue to be, electrophysiological, but a careful calibration of imaging signals with respect to electrophysiological recordings can extend our data set immeasurably, providing new insights into old problems.