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Patent Searching and Data


Title:
ZOOM LENS
Document Type and Number:
Japanese Patent JPH08106046
Kind Code:
A
Abstract:

PURPOSE: To provide a zoom lens suitable for a video camera and having a bright F number, a high variable power and a low cost.

CONSTITUTION: This zoom lens is, in order from the object side, composed of a first lens group 1 having a positive refractive power, a second lens group 2 having a negative refractive power and moving at the time of power variation, a third fixed lens group 3 having a positive refractive power and a fourth lens group 4 having a positive refractive power and compensating the movement of an image plane at the time of power variation, the fourth lens group 4 is, in order from the object side, composed of a lens having a positive refractive power, a lens having a negative refractive power and a lens having a positive refractive power, either of lenses having positive refractive powers and the lens having a negative refractive power are formed with plastic and the other lenses having positive refractive powers are formed of inorganic glass and the conditional relation: 60< ν4G is satisfied, where, ν4G is Abbe number of a lens made of inorganic glass in the fourth lens group.


Inventors:
SATO HIROSHI
Application Number:
JP24028394A
Publication Date:
April 23, 1996
Filing Date:
October 04, 1994
Export Citation:
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Assignee:
KONISHIROKU PHOTO IND
International Classes:
G02B13/18; G02B15/16; (IPC1-7): G02B15/16; G02B13/18