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Title:
VARIABLE POWER FINDER AND IMAGE PICKUP DEVICE
Document Type and Number:
Japanese Patent JP2005037791
Kind Code:
A
Abstract:

To provide a variable power finder that is small in size and excellent in optical performance, and also to provide an image pickup device using the finder.

The variable power finder is composed such that it is equipped with an objective optical system 1, a reverse optical system 2, and an eyepiece optical system 3 from the object side, that the third lens group G3 of the objective optical system 1 is composed of one lens prism P1 having at least one reflection surface, and that the following expressions are satisfied; f3/fw≥2.5, -1.0<(R32+R31)/(R32-R31)<1.0, L1/fw2≤0.45, and L2/fw2≥0.03 where f3 is the focal distance of the third lens group G3, fw is the focal distance in the wide-angle end of the objective optical system 1, R31 is the radius of curvature of the object side lens surface of the lens prism P1, R32 is the radius of curvature of the image side lens surface r6 of the lens prism P1, L1 is the air equivalent distance from an intermediate image forming surface to the object side lens surface of the lens prism P1, and L2 is the distance from the intermediate image forming surface to the image side lens surface r6 of the lens prism P1.


Inventors:
Tamura, Masaki
Application Number:
JP2003000276424
Publication Date:
February 10, 2005
Filing Date:
July 18, 2003
Export Citation:
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Assignee:
SONY CORP
International Classes:
G03B13/12; G02B13/18; G02B15/16; G02B15/163; G02B17/08; G02B23/14; G02B25/00; H04N5/225; (IPC1-7): G02B15/163; G02B13/18; G02B17/08; G02B25/00; G03B13/12; H04N5/225
Attorney, Agent or Firm:
船橋 國則