1. An autofocus method for a digital image acquisition device based on face detection, comprising: using a lens, image sensor and processor of a digital image acquisition device to acquire a digital image of a scene that includes one or more out of focus faces; detecting the one or more out of focus faces within the digital image by using one or more sets of classifiers trained on faces that are out of focus, wherein the one or more sets of classifiers are reference parameters that are calibrated to reference criteria including at least a set of faces that are out of focus; determining one or more sizes of the one of more respective out of focus faces within the digital image; determining one or more respective depths to the one or more out of focus faces based on the one or more sizes of the one of more out of focus faces within the digital image; adjusting one or more respective focus positions of the lens to focus approximately at the determined one or more respective depths; and acquiring one or more further images of scenes that include at least one of the one or more out of focus faces with the lens focused at the one or more respectively adjusted focus positions.