Title:
SMALL-SIZED LENS
Document Type and Number:
Japanese Patent JP3925748
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To attain the cost reduction and high performance of a telephoto lens while making the telephoto lens small in size by dividing the whole lens system into two front and rear groups, having a telephoto lens constitution in which the front group has a positive refractive power and the rear group has a negative refractive power and also satisfying specified conditional inequalities.
SOLUTION: This small-sized lens is constituted of three lenses as whole in order from an object side, that is, the front group whose refractive power is positive, in which a negative lens L1 whose concave face is confronted with an object, a biconvex lens L2 with the face of a strong curvature confronted with the object are arranged, and the rear group whose refractive power is negative, and which is constituted of a negative meniscus lens L3 whose concave face is confronted with the object. And, 0.90<L/f<1.05 is satisfied, provided that L denotes a length from the center position of the optical axis on the face arranged closest to the object to the image point position of the whole lens system and (f) denotes the focal distance of the whole lens system, and 0.18<D4/f<0.36 is satisfied, provided that D4 denotes a group distance between the front group and the rear group. Besides, two lenses L1 and L2 are formed of organic material.
Inventors:
Kazunori Ohno
Application Number:
JP12650697A
Publication Date:
June 06, 2007
Filing Date:
April 30, 1997
Export Citation:
Assignee:
Fujinon Co., Ltd.
International Classes:
G02B9/12; G02B13/02; G02B13/18; (IPC1-7): G02B9/12; G02B13/18
Domestic Patent References:
| JP7294815A |
Attorney, Agent or Firm:
Hiroshi Kawano