Title:
WIDE ANGLE ZOOM LENS
Document Type and Number:
Japanese Patent JPH05134181
Kind Code:
A
Abstract:
PURPOSE:To provide an ultra-wide angle zoom lens of a simple constitution having a wide angle of view and a bright f-number at a wide angle end by composing the lens of a first lens group, negative, a second lens group, negative, and a third lens group, positive. CONSTITUTION:A first lens group having a negative refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power are provided in this order from the object side, where the first to third lens groups are moved in zooming from a wide angle end to a telescopic end in such a way as to increase an interval between the first lens group and the second group once and then decrease it, and as to decrease an interval between the second lens group and the third lens group. By thus dispersing the negative refractive powers in the two lens groups, a synthesized refractive power can be increased by regulating the principal point interval for the first and second lens groups without increasing an aberration generated between both lens groups, thereby a back focus can be secured effectively, and an f-number can be set smaller.
Inventors:
TAKADA KATSUHIRO
Application Number:
JP32406291A
Publication Date:
May 28, 1993
Filing Date:
November 13, 1991
Export Citation:
Assignee:
OLYMPUS OPTICAL CO
International Classes:
G02B15/20; G02B15/177; (IPC1-7): G02B15/20
Attorney, Agent or Firm:
Koji Mukai