Minolta Company, Ltd.

Minolta

Kyoko Yamaguchi

Hiromu Mukai

Tetsuo Kohno

Hiroyuki Matsumoto

Jun Ishihara

Yutaka Inoue

Katsuto Tanaka

An optical system includes a first optical element formed of a noncrystalline polyester resin having a copolymer ratio of 9,9-bis [4(2-hydroxyethoxy) phenyl]fluorene in a range of 35 molar percent to 45 molar percent when the dicarboxylic acid component is 100 molar percent, and a second optical element formed of material incorporating an ultraviolet light absorption agent and disposed at least either anteriorly or posteriorly to the first optical element.

Optical system having an optical element made of resin

A zoom finder optical system of real image type of the present invention is provided with an objective lens system of a positive refractive power, a condenser lens of a positive refractive power and an eyepiece system of a positive refractive power from an object side. The objective lens system includes from the object side a first lens unit of negative refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power and a fourth lens unit of a positive refractive power.

Zoom finder optical system

An eyepiece for use in a viewfinder optical system has a wide dioptric power adjustment range. The eyepiece is provided with, from a side of a secondary-image plane formed by a first, a second, and a third relay lens, a first, a second, and a third eyepiece lens having a positive, a negative, and a positive refractive power, respectively. For dioptric power adjustment, the positive first eyepiece lens or the negative second eyepiece lens is moved in an optical axis direction.

Eyepiece

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Sakai, Japan

Kyoko Yamaguchi