Zoom lens and imaging apparatus including the same
AssigneeCanon Kabushiki Kaisha
InventorMasato Katayose
Life of this patent
Estimating the term…
Abstract
A zoom lens L0 consists of a first lens unit L1 having negative refractive power, a middle group Lm including one or more lens units, and a last lens unit having positive refractive power. The first lens unit L1 includes a first negative lens, a second negative lens, and a third negative lens that are arranged sequentially in an order from an object side to an image side. The number of negative lenses included in the first lens unit L1 is four or less. The middle group Lm includes a plurality of cemented lenses each having a cemented surface that is convex toward the object side, and includes a lens element Ln that is disposed closest to the image side among lens elements having negative refractive power included in the middle group Lm. The zoom lens L0 satisfies a predetermined inequality.
Claims17
A zoom lens comprising a first lens unit having negative refractive power, a middle group consisting of a second lens unit having positive refractive power and a third lens unit disposed closer to an image side with respect to the second lens unit and having positive refractive power, and a last lens unit having positive refractive power that are arranged in an order from the object side to an image side,
- wherein a spacing between adjacent lens units, among the lens units, changes in zooming,
- wherein the zoom lens includes an aperture stop,
- wherein the first lens unit includes a first negative lens, a second negative lens, and a third negative lens that are arranged in the order from the object side to the image side,
- wherein a number of the negative lenses included in the first lens unit is three or four,
- wherein the middle group includes a plurality of cemented lenses each having a cemented surface that is convex toward the object side, and includes a lens element Ln that is disposed closest to the image side among lens elements having negative refractive power included in the middle group, and
- wherein the following inequalities are satisfied:
- 1.2<|f1|/fw<2.0,
- 0.5<L1s/Lsn<1.8, and
- 0.7<|fn|/Lsn<2.0,
- where f1 is a focal length of the first lens unit, fw is a focal length of the zoom lens at a wide angle end, L1s is a distance on an optical axis from a lens surface, of the zoom lens, disposed closest to the object side to the aperture stop at the wide angle end, Lsn is a distance on the optical axis from the aperture stop to a lens surface, of the lens element Ln, disposed closest to the image side at the wide angle end, and fn is a focal length of the lens element Ln.
Dependencies are inferred from the claim text.