1. A method for acquiring imagery in a large capture volume, including a series of images of a subject at a predetermined range of focus values, independent of feedback from a focus measurement value, the method comprising: (a) controlling, by a focus controller component, a controllable focusing component comprising a lens, to focus at a predetermined series of different values within a focus range, without any input from measurement of whether an image of an unconstrained subject to be acquired is in focus or out of focus, or other distance metrics to the subject; (b) acquiring a plurality of images of an iris of the subject; and (c) rejecting, by a sharpness and/or contrast detection component, a number of the most out-of-focus images based on measurement of focus on each of the acquired images.