A system for providing a predictive autofocus prior to capturing an image of an iris of a subject. A sequence of images of the subject may be taken with a visible light sensitive camera. A speed and/or location of the subject may be estimated from the images. An encounter may be when the subject is within focus of the camera or, in other words, a focus distance and subject distance coincide. The focus may be determined in accordance with an intensity variance determination of the subject in the image, and more particularly of a subject's eye within a window of an image. Upon an encounter, an image of the iris of the eye may be captured with an infrared sensitive camera.