Despite much excellent work over the years, the vast history of scientific filmmaking is still largely unknown. Historians of science have long been concerned with visual culture, communication and the public sphere on the one hand, and with expertise, knowledge production and experimental practice on the other. Scientists, we know, drew pictures, took photographs and made three-dimensional models. Rather like models, films could not be printed in journals until the digital era, and this limited their usefulness as evidence. But that did not stop researchers from making movies for projection at conferences as well as in lecture halls, museums and other public venues, not to mention for breaking down into individual frames for analysis. Historians of science are more likely to be found in the library, archive or museum than the darkened screening room, and much work is still needed to demonstrate the major effects of cinema on scientific knowledge. Film may have taken as long to change science as other areas of social life, but one can begin to glimpse important ways in which 'image machines' (cameras, projectors and the like) were beginning to mediate between backstage experimental work and more public demonstration even around 1900.