| 摘要 |
A Keplerian zoom finder optical system has an objective lens comprising, in succession from the object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power and a third lens unit of positive refractive power and having positive refractive power as a whole, and an eyepiece of positive refractive power for enlarging and observing the focus image of the objective lens therethrough. The air gap between the first lens unit and the second lens unit is varied to thereby vary finder magnification. The Keplerian zoom finder optical system satisfies a predetermined condition.
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