The aim of ethnomiotics is not so much to make ethnography with methods born for other purposes, but to question the conditions of possibility of ethnographic practices from a semiotic point of view. In this perspective, participant observation is not a method; it's a scientific problem. How and within what limits does participation in a given practice allow the researcher to grasp its emerging effects of meaning, through the description of its formal side? If the practice belongs to a culture that is not familiar to the observer, how can the discrepancies between the respective codes be remedied? To what extent do the interpretations provided by the Other with whom we interact help understanding? When is it necessary to detach from it in order to provide a structural explanation? These questions, quite recurrent in ethnological literature, will be addressed starting from a case study: the participant observation of the Orthodox liturgy of small vespers in the Cathedral of St. Mary Magdalene in Warsaw. Originally, the observation was intended to identify and describe structures of religious discourse that partly allowed communication between Ukrainian refugees and the local population. The presentation will focus mainly on the methodological problems and the difficulties that observation encounters upstream of the description. At the same time, given the observable nature of conflicts and frictions between codes, ethnosemiotic reflection is proposed as unavoidable in the broader framework of semiotic research on culture.