Augmented and mixed reality is already considered as needful technology of the modern production systems. It is primarily employed to virtualize proper digital content, mainly related to 3D objects, into the human visual field allowing people to visualize and understand complex spatial shapes, their mutual relations, and positioning. Yet, the huge potential of the technology is waiting to be revealed in its usage for collecting and recording human observations and inferences about the context of the production environment. Its bi-directional interface makes it the most direct and the most efficient knowledge capturing means to date. The paper presents the challenges and benefits that come from the usage of a conceptual interface of an mixed reality application that is designed to collect data, semantics and knowledge about the production context directly from the man-in-process. As a production environment for the development, implementation, and testing of mixed reality applications for this purpose, various processes for the assembly and maintenance of medium-voltage equipment were used