| 摘要 |
PURPOSE:To execute an automatic focus adjustment even in case of a lens system whose back-focal distance quantity is small by using a part of lenses for constituting a lens system, for a minute quantity variation of an optical path length, and vibrating it by a minute distance in the optical axis direction. CONSTITUTION:As for a lens 16 for optical path length minute vibration which is one piece of lenses for constituting a lens system 6, a vibrating device 17 is provided so that said lens is vibrated by a minute distance as shown by arrows (e), (f) in the optical axis direction of the lens system 6. As for the vibrating device 17, for instance, an electromagnetic device is used, and its actual example is shown in the figure. The lens 16 for optical path length minute variation is fixed to a lens holder 19 by a holding ring 18, one end of a diaphragm 20 is fixed to the lens holder 19 by a screw, etc. through a ring 21, its other end is fixed to a lens barrel 26 by a screw through a spacer 22, a magnetic iron plate 23, a permanent magnet 24 and a magnetic iron plate 25, and a coil 27 is fixed to the lens holder 19 by means of adhesion, etc. |
