| 摘要 |
A Keplerian variable magnification finder includes, in order from the object side, an objective system having a positive refracting power as a whole; an image erecting system for erecting an intermediate image formed by the objective system; and an eyepiece system having a positive refracting power as a whole. The objective system including a first lens unit having a negative refracting power; a second lens unit having a positive refracting power; and a third lens unit having a positive refracting power. When the magnification of the finder is changed, the second and third lens units can be moved along the optical axis. The objective system satisfies the following conditions at the same time:0.1<|f1/(fS Z)|<0.40.2<f3/(fS Z)<0.53where f1 is the focal length of the first lens unit, f3 is the focal length of the third lens unit, fS is the intermediate focal length of the objective system (fS=(fWfT)+E,fra 1/2+EE when focal lengths of the objective system at low and high magnification positions are represented by fW and fT, respectively), and Z is a variable magnification ratio (Z=fT/fW).
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