Interaction in an immersive virtual environment is limited by imperfect depth cues, unstable hand placement in midair, and so on. In this study, we summarize the design and implementation of a magic lens interface within an immersive virtual environment using a handheld device such as a personal digital assistant (PDA) or an ultra mobile personal computer (UMPC). Our interface simplifies the selection and manipulation processes using image-based interaction techniques. An empirical study shows the effectiveness of the proposed interface for selecting 3D objects, especially when the target is small or in motion.