1. A method of digital image processing using face detection, comprising: acquiring a scene with a digital image acquisition device including multiple features; identifying a first group of pixels that correspond to a first feature of a face within the scene; adjusting an optic in real time using a MEMS component to a first focus position to focus the device on the first feature; capturing a first digital image at the first focus position; applying multiple focus-specific classifier chains, including a first trained to match substantially out of focus faces, and a second trained to match slightly out of focus faces, and a third focus-specific classifier chain trained to match sharply focused faces; and when a second face is determined not to be sharply focused as significantly matching the first or second focus-specific classifier chains, or both, adjusting focus position using a MEMS component one or more times based on a degree of focus determined at one or more preceding focus positions and, such as to ultimately focus on the second face using a series of one or more selected smart-focus adjustments based on application of the focus-specific classifier chains; and one or more of (i), (ii)(a), or (ii)(b), as follows: (i) wherein when the second face is determined to be substantially unfocused as best matching the first focus-specific classifier chain, then the adjusting comprises coarsely adjusting to a second focus position and repeating the applying of the multiple focus-specific classifier chains, or (ii) wherein when the second face is determined to be slightly unfocused as best matching the second focus-specific classifier chain, then the adjusting comprises finely adjusting to a second focus position and (a) repeating the applying of the multiple focus-specific classifier chains one or more times until a best match is achieved with the third focus-specific classifier chain; or (b) repeating the applying of the second focus-specific classifier chain until a focus position is achieved between two slightly unfocused positions in front of and behind the second face; and capturing a second digital image having a second feature at the second focus position; registering the first and second digital images including the first and second features; and storing, transmitting, combining, capturing or displaying the first and second digital images together, or combinations thereof.