1. A method of capturing image data for iris code based identification of vertebrates, including humans, the method comprising the steps of: recording a digital image of an eye with a camera equipped with at least two light sources that have a fixed spatial relationship to an object lens of the camera; locating the eye in the digital image by detecting a specularity pattern that is created by reflection of light from said at least two light sources at a cornea of the eye; and calculating information on the position of the camera relative to the eye on the basis of said fixed spatial relationship between the light sources and the object lens and on the basis of said specularity pattern.