Zoom lens system and camera including the same
AssigneeCanon Kabushiki Kaisha
InventorShinichiro Saito
Life of this patent
Estimating the term…
Abstract
Provided is a zoom lens system including, in order from an object side to an image side: a first lens unit having a positive optical power; a second lens unit having a negative optical power; a third lens unit having a positive optical power; a fourth lens unit having a negative optical power; and a fifth lens unit having a positive optical power. In this zoom lens system, magnification sharing between the fourth lens unit and the fifth lens unit, and a movement amount of the second lens unit as a principal magnification lens unit are set appropriately, so as to realize a high zoom ratio and high optical performance over an entire zoom range.
Claims10
A zoom lens system, comprising, in order from an object side to an image side:
- a first lens unit which has a positive optical power and does not move for zooming;
- a second lens unit having a negative optical power;
- a third lens unit having a positive optical power;
- a fourth lens unit having a negative optical power;
- and
- a fifth lens unit which has a positive optical power and moves along a locus convex to the object side for zooming,
- wherein the second lens unit has a largest ratio of an imaging magnification at a telephoto end to an imaging magnification at a wide-angle end among lens units included in the zoom lens system;
- and
- wherein the following condition is satisfied
- 1.4<max|β4×β5|/min|β4×β5|<14,
- where max|β4×β5| denotes a maximum value of a product of a lateral magnification of the fourth lens unit and a lateral magnification of the fifth lens unit in zooming from the wide-angle end to the telephoto end, and min|β4×β5| denotes a minimum value of a product of the lateral magnification of the fourth lens unit and the lateral magnification of the fifth lens unit in zooming from the wide-angle end to the telephoto end.
A zoom lens system, comprising, in order from an object side to an image side:
- a first lens unit having a positive optical power;
- a second lens unit having a negative optical power;
- a third lens unit having a positive optical power;
- a fourth lens unit having a negative optical power;
- and
- a fifth lens unit which has a positive optical power and moves along a locus convex to the object side for zooming,
- wherein the second lens unit has a largest ratio of an imaging magnification at a telephoto end to an imaging magnification at a wide-angle end among lens units included in the zoom lens system;
- and
- wherein the following conditions are satisfied:
- 1.4<max|β4×β5|/min|β4×β5|<14;
- and
- 0.4<st2/fw<20,
- where max|β4×β5| denotes a maximum value of a product of a lateral magnification of the fourth lens unit and a lateral magnification of the fifth lens unit in zooming from the wide-angle end to the telephoto end, min|β4×β5| denotes a minimum value of a product of the lateral magnification of the fourth lens unit and the lateral magnification of the fifth lens unit in zooming from the wide-angle end to the telephoto end, st2 denotes a movement amount of the second lens unit in zooming from the wide-angle end to the telephoto end, and fw denotes a focal length of the zoom lens system at the wide-angle end.
Dependencies are inferred from the claim text.