Digital tabletops have become a natural medium for collaborative planning activities involving maps. Such activities are typically mixed-focus, where users switch between high-level and detailed views of the map and between individual and collaborative work. A wide range of view-sharing techniques such as lenses, zooming and radar views provide both shared and individual access to the same workspace. However, it is not yet sufficiently clear how the choice of view techniques affects collaboration in mixed-focus scenarios. In this paper, we explore the effect of different view techniques on collaborative map-based tasks around tables. We report on two studies in the context of military planning, one in a controlled environment and one in an open-ended scenario carried out by domain experts. Our findings show how the success of different techniques is sensitive to the form of collaboration and to the proximity of work on the table.