The promises and visions arising from scientific discoveries, technological breakthroughs, and the emergence of technological fields are by nature uncertain and inaccurate. This paper suggests that a reasonable way to expose more accurately the conditions of incomplete knowledge, imperfect inference, and open-endedness surrounding emerging technological fields is to look at actors' shared expectations or common guiding images that function as scenarios. A rigorous theoretical framework and a methodological approach that exposes in a more accurate way foundations and generalizations underlying guiding images in emerging technological fields is developed. We undertake co-classification analysis of patent data, content analysis of patents, and analysis of firm communication in order to map, analytically distinguish generalizations, and judge (using domain experts) the foundations of competing guiding images in the emerging field of cellulosic bioethanol. We uncover two competing guiding images, an 'expectation-based' guiding image of 'cellulose ethanol manufacturing', and a more radical development, an 'anticipation-based' guiding image of 'plant self-production'. Further, we identify a wild card, that of algae-based photosynthetic ethanol production. Together the exposure and the analysis of the foundations of two competing guiding images and a wild card in the field of cellulose ethanol provide previously unmatched substantiation of open-endedness of expectations in an emergent technological field.