An optical system is able to capture images of at least a portion of a candidate's face within a near field, a medium field, and a far field. For images captured within the near field, data representing the candidate's iris may be captured from the image and compared to know iris data. For images captured within the medium field, data representing the candidate's iris and facial featured may be captured from the image and compared to know iris data and facial data. For images captured within the far field, data representing the candidate's facial features may be captured from the image and compared to know facial data.