Zoom lens
AssigneeCanon Kabushiki Kaisha
InventorsHitoshi Mukaiya, Akihisa Horiuchi, Yasunori Murata, Akihiro Nishio
Life of this patent
Estimating the term…
Abstract
A zoom lens comprising a first lens unit of positive power, a second lens unit of negative power as the variator, a third lens unit of negative power as the compensator, and a fourth lens unit of positive power stationary during zooming, the fourth lens unit being composed of a bi-convex first lens, a positive second lens, a negative third lens of strong concave curvature at the front, a positive fourth lens, a fifth lens of strong concave curvature at the rear, and a positive sixth lens, and satisfying the following condition: 0.5<D/Fw<1.5 where D is the air separation between the fourth and fifth lenses, and Fw is the shortest focal length of the entire lens system.
Claims4
A zoom lens comprising:
- when counted from the object side,
- a first lens unit having a positive refractive power;
- a second lens unit having a negative refractive power and arranged to move along an optical axis for varying the image magnification;
- a third lens unit arranged to move along the optical axis as the image magnification is varied;
- and
- a fourth lens unit having a positive refractive power and arranged to be stationary,
- said fourth lens unit including a ti-convex first lens, when counted from the object side, a positive second lens, a negative third lens having a strong concave surface facing the object side, a positive fourth lens, a fifth lens having a strong concave surface facing the image side, and a positive sixth lens, and satisfying the following condition:
- 0.5<D/Fw<1.5
- where D is the air separation between said positive fourth lens and said fifth lens, and Fw is the shortest focal length of the entire lens system.
Dependencies are inferred from the claim text.