The present disclosure describes imaging techniques and devices having improved autofocus capabilities. The imaging techniques can include actively illuminating a scene and determining distances over the entire scene and so that a respective distance to each object or point in the scene can be determined. Thus, distances to all objects in a scene (within a particular range) at any given instant can be stored. A preview of the image can be displayed so as to allow a user to select a region of the scene of interest. In response to the user's selection, the imager's optical assembly can be adjusted automatically, for example, to a position that corresponds to optimal image capture of objects at the particular distance of the selected region of the scene.