| 摘要 |
PURPOSE:To provide good operability and to permit satisfactory correction of a fluctuation in aberration arising from zooming by moving a 2nd lens group of a negative refracting power to an object side so that focusing from infinity to a close distance object is permitted and that always the combined positive refracting power is maintained as a focusing system. CONSTITUTION:The focusing system F of a zoom lens consisting, successively from the extreme object side, the focusing system F, zoom system Z and relay system R is constituted, successively from the object side, of the 1st lens group 1 having the negative refracting power, the 2nd lens group 2 having likewise the negative refracting power and the 3rd lens group 3 having the positive refracting power. The 2nd lens group 2 having the negative refracting power is moved to the object side at the time of focusing from the infinity to the close distance object. Always a positive value is maintained for the combined refracting power as the focusing system F. The satisfactory correction of the fluctuation in the aberration arising from the focusing is thereby permitted while the effective aperture diameter is maintained small in a variable power region including a super wide angle of view.
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