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US 4,380,376 AGranted
Zoom objective
AssigneeCanon Kabushiki Kaisha
InventorsShigeyuki Suda, Kazuo Tanaka
Life of this patent
Estimating the term…
Abstract
A zoom objective is composed of three components of which the first and the third each perform a one-round axial movement over the range of variation, while the second simultaneously performs a monotonic axial movement in one direction.
Claims3
A zoom objective comprising:
- a first lens group, a second lens group and a third lens group arranged in the order mentioned from an objective end to an image end;
- said first lens group having a positive refractive power and being axially movable forward and then rearward when zooming from a wide angle to a telephoto setting;
- said second lens group having a negative refractive power and being axially movable from the objective end to the image end when zooming from the wide angle to the telephoto setting;
- and
- said third lens group having a positive refractive power and being axially movable forward and then rearward when zooming from the wide angle to the telephoto setting.
2 more elements
A zoom objective comprising:
- a first lens group, a second lens group, and a third lens group arranged in the order mentioned from an objective end to an image end;
- said first lens group having a positive refractive power and focusing and compensating functions, and moving first toward the objective end and then toward the image end during zooming from a wide angle position to a tele position;
- said second lens group having a negative refractive power and magnificating function, and moving only in one direction from the objective end to the image end during zooming from the wide angle position to the tele position;
- and
- said third lens group having a positive refractive power and compensating function, and moving first toward the objective end and then to the image surface end during zooming from the wide angle position to the tele position.
2 more elements
Dependencies are inferred from the claim text.