Title:
【発明の名称】実像式変倍ファインダー光学系
Document Type and Number:
Japanese Patent JP3384893
Kind Code:
B2
Abstract:
A real image type zoom finder optical system is constructed by an objective optical system, an erect orthoscopic optical system and an eyepiece optical system sequentially arranged from an object side. The objective optical system is composed of first to fourth lens groups each constructed by a single lens. The erect orthoscopic image optical system is composed of two erect prisms. The eyepiece optical system is composed of one lens group. A front face of the second lens group is constructed by an aspherical surface such that the first, second, third and fourth lens groups respectively have positive, negative, positive and positive refracting powers. A real image formed by the objective optical system is focused and formed within the erect orthoscopic image optical system. A zooming operation is performed by moving the second lens group from the object side to an eyepiece side on an optical axis of the finder optical system. A change in diopter of a finder caused by this zooming operation is corrected by an axial movement of the fourth lens group.
Inventors:
Nobuaki Ono
Application Number:
JP28137794A
Publication Date:
March 10, 2003
Filing Date:
October 20, 1994
Export Citation:
Assignee:
株式会社リコー
International Classes:
G03B13/06; G02B13/18; G02B15/16; G02B15/173; G03B13/12; G02B23/14; (IPC1-7): G02B15/16; G02B13/18; G03B13/12
Domestic Patent References:
| JP6289293A | ||||
| JP6102454A | ||||
| JP618780A |
Other References:
【文献】登録実用新案3000415(JP,U)
Attorney, Agent or Firm:
Shuji Sanada