| 摘要 |
A focussing apparatus for a camera, having an indicator for indicating the degree of blurring of an image produced by the taking lens, comprising a plano-concave lens and a plano-convex lens, of the same curvature, which accordingly have no refracting power when in contact with each other, disposed in the viewfinder's optical path. Signals from an object distance measuring means and a position detecting means for detecting the shifted position of the taking lens, are fed to a differential amplifier. The output of the differential amplifier, which corresponds to the degree of blurring of an image produced by the taking lens, causes the concave lens and/or the convex lens to shift so that the distance between these lenses is directly proportional to the degree of blurring and gives a visible indication of the same in the viewfinder.
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