Magic Lens is a small inset window embedded in a large context display, which provides an alternative view to the region of interest selected from the context view. This metaphor is used for 3D visualization in our Augmented Virtual Environment infrastructure, SCAPE (Stereoscopic Collaboration in Augmented and Projective Environments), which is composed of an immersive room display for a high level of detail, life-size virtual world and a workbench display for simplified god-like view to the world. A tangible Magic Lens is used on the workbench display to allow direct and intuitive selection of continuous levels of detail, bridging the gap between the two extreme levels of detail in SCAPE. This paper presents our first step to the user evaluations of tangible Magic Lens. We conducted two sets of user evaluations, one mainly testing the lens aspect ratio, and another for the lens size. For both of the tests, two types of tasks are conducted: information gathering and relating the detailed information with the context. We found that the aspect ratio of a lens plays more important role in user preference for smaller lenses than for larger ones. Mean while, the size of a lens is the most important factor that affects the user performance in the two types of tasks.