The endoscope (10) has a light exiting surface (49) which is formed at a distal end portion (19). A controllable light-refraction device (40) is arranged at the distal end portion, for controlling diffraction of illuminating light based on a malleable phase boundary surface (45) between the two fluids (44,46). An independent claim is included for method of illuminating an adjustable field of view of an endoscope.