| 摘要 |
PURPOSE:To shorten the total length of a small-sized variable power lens system and, at the same time, to simplify the mechanism, by changing the focal length of the entire lens system by moving the front element of the main lens system composed of the front element having a positive refracting power and a rear element having a negative refracting power and fitting an auxiliary lens system to the image side of the rear element. CONSTITUTION:A telephoto type main lens system I is constituted of a front element I a of a lens group having a positive refracting power and a rear element I b of a lens group having a negative refracting power. Variable power function is given to this main lens system I by fitting an auxiliary lens system IIto the image side of the rear element I b. Since the image plane moves when the auxiliary lens system II is fitted, movement of the image position is corrected by moving the front element I a.
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