US 4,391,488 AGranted

Mount device of an interchangeable lens

AssigneeNippon Kogaku K.K.

InventorsSunao Ishizaka, Toshiaki Hozumi

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Abstract

In an interchangeable lens having a mount mountable on a camera incuding an electric circuit associated with exposure control and a displaceable actuating member for correcting the electric circuit so as to be accommodated to the focal length of the interchangeable lens mounted, a signal member is provided projectedly from one end of the mount and engageable with the actuating member so as to cause said displacement when the interchangeable lens is mounted on the camera. The signal member has an engaging end portion engageable with the actuating member. The engaging end portion lies at a position determined relative to the mount for displacing the actuating member by an amount related to the logarithm of the focal length of the interchangeable lens.

Claims9

Dependent claims

In a lens system comprising an interchangeable lens having a mount mountable on a camera having an electric circuit associated with exposure control and a displaceable actuating member for correcting said electric circuit so as to be accommodated to the focal length of the interchangeable lens mounted, and a conversion lens having an optical system for converting the focal length of said interchangeable lens and mountable between said interchangeable lens and the camera, the improvement comprising:

a signal member provided on said interchangeable lens projectedly from one end of said mount and engageable with said actuating member so as to close said displacement when said interchangeable lens is mounted on the camera through said mount, said signal member having an engaging end portion engageable with said actuating member, said engaging end portion lying at a position determined relative to said mount for displacing said actuating member by an amount proportional to the logarithm of the focal length of said interchangeable lens;
and
a transmission member provided on said conversion lens and positioned between said signal member and said actuating member when said conversion lens is mounted, said transmission member being slidable by said signal member by an amount corresponding to the position of said engaging end portion and displacing said actuating member by an amount proportional to the logarithm of said focal length converted in response to said sliding and the mounting of said conversion lens onto the camera.

Dependencies are inferred from the claim text.