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Title:
PHOTOGRAPHIC LENS SYSTEM
Document Type and Number:
Japanese Patent JP2000180719
Kind Code:
A
Abstract:

To provide an extremely compact photographic lens system having high optical performance.

This system is provided with a front group F, a diaphragm A and a positive rear group R, and the rear group R is constituted of three lenses, a negative lens RL1, a positive lens RL2 and a positive lens RL3. With respect to the aspherical surfaces (*) of the rear group R, the maximum effective radius of the aspherical surface is expressed by (ymax), with reference to the arbitrary height (y) in a direction vertical with respect to the optical axis, satisfying 0.7ymax<y<1.0ymax, a conditional inequality 0.01<(x-x0)/(N'-N)<1.0 is satisfied. Here (X) represents the shifting amount of the aspherical surface in the optical axis(AX) direction with a vertical height with reference to an optical axis AX (a direction toward the object is get negative), x0 denotes the shifting amount of the aspherical surface in the optical axis AX direction with a vertical height with reference to the optical axis AX of a reference spherical surface (the direction toward the object is get negative), N denotes a refractive index with respect to a d line of a medium which is closer to the object than the aspherical surface. N' represents a refractive index with respect to a d line of a medium, which is closer to an image side rather than the aspherical surface in the inequality.


Inventors:
Isono, Masafumi
Application Number:
JP1998000353189
Publication Date:
June 30, 2000
Filing Date:
December 11, 1998
Export Citation:
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Assignee:
MINOLTA CO LTD
International Classes:
G02B13/18; G02B9/34; G02B9/60; G02B13/00; (IPC1-7): G02B13/18



 
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