Title: Zoom optical system

Abstract: A zoom optical system is composed of a positive focusing lens group, a negative variating lens group, a negative compensating lens group and a positive rear fixed lens group. A rotating grooved cam moves the variating lens group and the compensating lens group in a given relation to each other along the optical axis in the normal focusing range. The focusing lens group is moved along the optical axis normal range for focusing. The variating lens group is kept stationary on the optical axis while the compensating lens group is moved along the optical axis during close-range focusing.

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Other info:

Inventors: Sakaguchi, Keiichi (Yokohama, JP)
Someya, Atsushi (Machida, JP)

Application Number: 737157
Filing Date: 1976-10-29
Publication_date: 1979-01-02
Assignee: Canon Kabushiki Kaisha (Tokyo, JP)
Primary Class(es): 359/693 359/706
Other Classes:
US Patent Ref:

3613544	Oct, 1971	Plihal et al.	350/187.
3655271	Apr, 1972	Suzuki	350/187.
3661445	May, 1972	Someya	350/186.
3731987	May, 1973	Iida et al.	350/187.
3773402	Nov, 1973	Gela et al.	350/184.

Other Refs:
Primary Examiner: Clark, Conrad J.
Assistant Examiner:
Attorney: Toren, McGeady and Stanger