Title:
ZOOM LENS
Document Type and Number:
Japanese Patent JPH04102815
Kind Code:
A
Abstract:
PURPOSE:To compensate aberrational variation excellently by providing 1st - 4th lens groups in order from an object side and providing the 3rd lens group with a biconvex lens and a negative meniscus lens and the 4th lens group with a negative meniscus lens, a biconvex lens, and a positive lens. CONSTITUTION:The 1st lens group I with positive refracting power, the 2nd lens group II with negative refracting power, the 3rd lens group III with positive refracting power, and the 4th lens group IV with positive refracting power are arranged in order from the object side. Those 1st and 3rd lens groups I and III are fixed and the 2nd lens group II is moved in one direction to vary the power. The 3rd lens group III is formed of the biconvex lens and the negative meniscus lens which has a large-curvature concave surface on the object side. The 4th lens group IV is formed of the negative meniscus lens, biconvex lens, and the positive lens and aberrational variation in focusing from a short- distance body to an infinite-distance body, specially, a curvature of field and astigmatism are compensated. Thus, the zoom lens which is thus formed meets requirements shown by inequalities (1) - (4).
Inventors:
HORIUCHI AKINAGA
Application Number:
JP22079490A
Publication Date:
April 03, 1992
Filing Date:
August 21, 1990
Export Citation:
Assignee:
CANON KK
International Classes:
G02B15/16; (IPC1-7): G02B15/16
Domestic Patent References:
| JPS6468709A | 1989-03-14 | |||
| JPH02204791A | 1990-08-14 | |||
| JPH01147595A | 1989-06-09 |
Attorney, Agent or Firm:
Giichi Marushima (1 person outside)