US Patent 7298414 Digital camera autofocus using eye focus measurement

Viewfinder apparatus, methods, and digital cameras that provide autofocus using retroreflected eye focus measurements. When a user looks at a part of a scene that is the intended subject of the image, his or her eye is correctly focused. The present invention measures the focus distance of the eye when the eye is focused on the desired location in the scene, and then uses the measured distance to set the focus of the camera.