The present disclosure is directed towards a compact, mobile apparatus for iris image acquisition, adapted to address effects of ocular dominance in the subject and to guide positioning of the subject's iris for the image acquisition. The apparatus may include a sensor for acquiring an iris image from a subject. A compact mirror may be oriented relative to a dominant eye of the subject, and sized to present an image of a single iris to the subject when the apparatus is positioned at a suitable distance for image acquisition. The mirror may assist the subject in positioning the iris for iris image acquisition. The mirror may be positioned between the sensor and the iris during iris image acquisition, and transmit a portion of light reflected off the iris to the sensor.