A system, method, and computer program product are provided for automatically progressively determining focus depth estimates for an imaging device from defocused images. After a depth-from-defocus (DFD) system generates sometimes-noisy estimates for focus depth and optionally a confidence level that the focus depth estimate is correct, embodiments of the present invention process a sequence of such input DFD measures to iteratively decrease the likelihood of focus depth ambiguity and to increase an overall focus depth estimate confidence level. Automatic focus systems for imaging devices may use the outputs of the embodiments to operate more quickly and accurately, either directly or in combination with other focus depth estimation methods, such as calculated sharpness measures. A depth map of a 3D scene may be estimated for creating a pair of images based on a single image.