In this paper we present a novel interface for mobile map navigation based on Semi-Automatic Zooming (SAZ). SAZ gives the user the ability to manually control the zoom level of an SDAZ interface, while retaining the automatic zooming characteristics of that interface at times when the user is not explicitly controlling the zoom level. In a user study conducted using a realistic mobile map with a wide scale space, we compare SAZ with existing map interface techniques, multi-touch and Speed-Dependent Automatic Zooming (SDAZ). We extend a dynamic state-space model for SpeedDependent Automatic Zooming (SDAZ) to accept 2D tilt input for scroll rate and zoom level control and implement a dynamically zoomable map view with access to high-resolution map material for use in our study. The study reveals that SAZ performs significantly better than SDAZ and that SAZ is comparable in performance and usability to a standard multi-touch map interface. Furthermore, the study shows that SAZ could serve as an alternative to multi-touch as input technique for mobile map interfaces.