Optical: systems and elements – Prism – With reflecting surface
Patent
1991-04-08
1992-09-29
Hix, L. T.
Optical: systems and elements
Prism
With reflecting surface
359701, G03B 118
Patent
active
051517299
ABSTRACT:
A zoom lens barrel comprises a plurality of lens groups; a fixed barrel having integrally and securely a mount portion for mounting the zoom lens barrel on the camera body; a zoom operation ring which is moved along an optical axis relative to the fixed barrel and causes lens groups associated with zooming to shift along the optical axis so as to execute a zooming action; a focus operation ring which is rotatably supported by the zoom operation ring and is moved with the zoom operation ring along the optical axis, and causes lens groups associated with focusing to shift along the optical axis through its own rotation so as to execute a focus action; and a cam ring which during the focus action cooperates with the focus operation ring and is moved along the optical axis relative to the fixed barrel to thereby shift lens groups associated with the focusing along the optical axis, and during the zooming action interlocks with the zoom operation ring to rotate to thereby shift the lens groups associated with the zooming along the optical axis. A first closest photographing distance limit mechanism acts between the focus operation ring and zoom operation ring. A second closest photographing distance limit mechanism acts between the fixed barrel and the cam ring. Within a specified focal length range the rotation of the focus operation ring is restrained by the second limit mechanism while in the focal length range other than the specified range the rotation of the focus operation ring is restricted by the first limit mechanism, thereby ensuring the optimum restriction of the closest photographing distance at any focal lengths.
REFERENCES:
patent: 4848884 (1989-07-01), Enomoto
Gray David M.
Hix L. T,.
Nikon Corporation
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