A system for measuring aberrations in an eye. The system comprises: a projecting optical system (12, 14, 16, 18) producing light to be delivered onto a retina of an eye (40)； an adjustable telescope (30) which compensates the light to be delivered onto the retina of the eye (40) for aberrations in the eye (40), the adjustable telescope (30) being positioned in an optical path between the projecting optical system and the eye (40)； a wavefront sensor (50) receiving light returned by the retina from the imaging system and detecting an amplitude and phase of a wavefront of the received light； a target (90) that is made visible to the eye (40)； a movable stage (72) on which the wavefront sensor (50), the target (90) and a movable lens (32/132) of the adjustable telescope are all mounted and are moveable with respect to a fixed lens (34/134) of the telescope to correct for defocus aberrations of the eye, and an aperture (36, 56) that blocks any rays outside the angular dynamic range of the wavefront sensor (50) so that no mixing or measurement confusion occurs.
