This paper aims to trace individual as well as collective aspects of ‘sight styles’ in diagnostic computed tomography. Radiologists need to efficiently translate the visualized data from the living human body into a reliable and significant diagnosis. During this process, their visual thinking and the created images are incorporated into a complex network of other visualizations, communication strategies, professional traditions, and (tacit) visual knowledge. To investigate the interplay of collective as well as individual dimensions of diagnostic seeing, the concept of (...) ‘sight collective’ (Sehkollektiv) is developed. On the one hand, this concept is based on critical reading of Ludwik Fleck’s epistemological writings and his notions of thought collective (Denkkollektiv) and thought style (Denkstil). On the other hand, it is tested by means of qualitative empirical studies in a radiological university clinic (participatory observations and informal interviews). By employing this approach, the paper traces the collective foundations of a certain diagnostic sight. Moreover, it shows how the individual abilities of radiologists to perform stylized seeing rely remarkably on software-based interactions with the processed images and on tacit dimensions of visual knowledge. (shrink)