1. A method of estimating a blur kernel distribution for visual iris recognition, said method comprising the steps of: determining a first mathematical relationship between an in-focus position of a camera lens and a distance between the lens and an iris whose image is to be captured by the lens; estimating a second mathematical relationship between the in-focus position of the lens and a standard deviation defining a Gaussian blur kernel distribution; predicting a position of an eye of a living being at a future point in time; adjusting a focus position of the camera lens based upon the predicted position of the eye; using the camera lens with the adjusted focus position to produce an image of the living being's eye at the point in time; sensing an actual position of the living being's eye at the point in time; using the first mathematical relationship to ascertain a desired focus position of the lens based upon the actual position of the living being's eye at the point in time; using the second mathematical relationship to calculate a standard deviation defining a Gaussian blur kernel distribution, the calculating being based upon a difference between the adjusted focus position and the desired focus position of the lens; and digitally unblurring the produced image by using the blur kernel distribution defined by the calculated standard deviation.