发明授权
US3969018A Objective system with zoom lens for photographic apparatus 失效
用于摄影器材的变焦镜头的客观系统

Objective system with zoom lens for photographic apparatus
摘要:
An objective system for motion picture cameras wherein a zoom lens is installed in a barrel and the barrel is surrounded by two ring-shaped selectors. The rear selector is rotatable to change the focal length of the lens by moving the optical elements of the rear group of optical elements of the lens with and relative to each other in the direction of the optical axis. The front selector is rotatable within a first angle to focus the image of a subject which is located at a distance of 5 ft. or more from the barrel, and within a second angle to focus the image of a subject prior to the making of close-up shots. The front selector moves the optical elements of the front group of optical elements of the lens during rotation within the first angle and the optical elements of the second group during rotation within the second angle. The focussing for close-up shots can be made after the focal length of the lens is reduced to a minimum value.
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